I don’t know how to handle this, help please

But yes,that aside,tackle toy situation first,tell your MIL outright that any gifts she buys your own kids this year they will be taking home with them,why shouldnt they? If theyre a gift for that child? If not tell her then you dont want nor need them? Id also refuse to go at christmas or birthdays unless she does allow that to happen.(has she never come to your house to bring their presents,ever,?in which case it makes it harder for her to look 'mean' like shes giving a gift then taking it back?tell her she& their grandad are both welcome to come visit& bring gifts TO YOUR HOUSE,then its easier to accept the gift as 'belonging to that child,in their own home' i personally would let child/children look at each gift then remove them somewhere else by saying "thank you for that lovely toy grandma,lets put it in toy box/bedroom'/wherever, now for later"-she can hardly snatch it back from you/or child then without looking like a mean witch can she?Or give a party somewhere else,like a play place,popular now if theyre getting older(usually age 4-ish upwards) and invite GP's to that,if she brings a gift,take it along with everyone elses,putting them all in a big lidded box to be opened later,if she doesnt bring a gift,tell her to send it to your house later,if she doesnt send or bring one tell her afterwards(when kids cant hear) you dont want it then unless its theirs TO KEEP.this is not teaching your kids not to share,its teaching your MIL boundaries/expected behaviours of how fairly you'd like your own children to be treated.Im also not convinced your own husband couldnt speak up & deal with this to his own mum either,so thats maybe another,different issue?Tell them ALL youd like your own family xmas this year,then get on with that,if they want to bring gifts,TO YOUR CHILDREN,make them welcome,at arranged time,maybe teatime or before bedtime?for an hour or two?I appreciate your kids do play with isobel,but its not sounding to me like they are actually 'fond' of her?more like they are all there together and theyre expected to play/ share with her? Not something they'd choose to do given the choice?(as they are starting to question so many things,theyre obviously strating to think things over for themselves now and not liking a lot about this unruly child who hurts them& 'steals' their things?(in their minds)and no, im not against 'non-blood' related children,some of my own older kids have their partners first child with them and they have 'mingled' with my own GC really well,i dont treat them any different,they all get THEIR OWN presents,TO TAKE HOME,or do with as they wish,i would also be free to be able tell that child off if it were necessary,if doing something wrong,whether its my natural GC or not.i see blatent 'favouritism' here for isobel,yet cant see why,? Unless as i said,that answer lies with your MIL showing 'faves' for her other son?That is another matter for your hubby to tackle with his own mother.But yes you will have to stand up to them all for your own kids sake,and maybe they could,for a little while,spend less time with isobel if its making them upset?Or perhaps they could visit GP's on different days,why always all together?(id still ask FIL to bring any toys that belong to your children especially, to your house for them to keep,why should they not have them,yet theres a different rule for isobel to take what's not even her own toys?Its not right nor fair,i agree with some others should SAME RULES FOR ALL,or no rule.

I think what I'd say to my children is "It's quite a complicated situation, and I am as confused as you are about what we should all be doing. It's not Isabel's fault. All we can do for now is be the best people we can be and hope it gets easier to understand in the end" It might be easier for the kids to accept if they know the adults are finding it hard too

I feel very sorry for you muffin.... you came here for advice and have found yourself being criticised which seems unfair. Please don’t doubt your own parenting skills or the fact that you care about the people involved in this difficult situation. We are all unique - including ‘Isabel’ - and should be respected for this. I would ask for advice from people who genuinely care about you and yours if I were you. All the best x

I don't know how well your children could understand this, but I would try to explain to them something of 'Isabel's' situation- that she has no proper Daddy or Granny and no brothers or sisters to play with and so she doesn't understand how to share or play nicely with other children and gets easily upset. Explain that their Granny feels sorry for her and is trying make her feel happy and welcome by letting her play with their toys and putting her picture up.
Then I suggest you explain the way your children feel to your MiL and ask for her advice on how to explain to your children why their toys are disappearing from her house. If she 'gets' the problem then fine, if not then any presents they receive from her from now on must be brought home.
By the way, there are absorbent sheets you can buy to put over a chair before she sits on it- my DD is using them while she toilet trains our DGS. As has been suggested up-thread I wouldn't make a fuss about the wetting or clothes removal, so she realises that is not a good way to get attention.
Good luck and I hope the situation can be resolved without hostilities!

Im not sure if BIL's partner is there with them for these visits or not?i presumed that it meant BIL is sent along with isobel on his own? but then theres no one to make isobel behave as her mums not there& hes not allowed to? Seems a very odd situation to me,yes very odd,could it be that isobels mum lets her get away with everything/is very soft with her,in order to make it up to her for a lack of her father? But that surely doesnt mean youve to let them hurt other kids or steal their things? If BIL has to 'be a parent' to her then that is what he should be doing- 'parenting' her- if she needs telling off ,do it, if she needs a toy taking from her at end of visit,with a firm "no that's to stay here" then that's what should happen.You seem to have right ways of showing your own kids how to behave muffinthemoo,but this childs mum does not- and everyone is pussyfooting around speaking out about it-im afraid you will have to.your MIL sounds as though shes very controlling,but that shes lost the 'control battle' to isobels mother,so theyre all doing what she wants now.and your hubby& his brother sound too weak to stand up to their own mum im sorry to say.But im not sure where this taking down the photos of her own actual GC in favour of isobel comes in?im inclined to say either isobels mum has 'leaned on' your MIL over this or your MIL has some kind of weird behaviour issues your not privvy to,thats worsening as she gets older perhaps? But i personally wouldnt dream of doing that to my GC,i was given a school photo recently of my sons partners child,i proudly put it on display with photos of my own children & Grandchildren.TOGETHER.i certainly wouldnt have took my natural GC's photos down.I find that very odd behaviour indeed.i think id want less to do with all of them muffin.

muffinthemoo
Dear Muffin, I started reading the responses and found many with which i agree and some not, but decided to write before reaching the end of reading all for sake of time as I have to get on with a commitment I took on - so apologies.

Firstly, I want to say that I remember you from previously and have a strong recollection of your very kind common sense and good humour. This comes across abundantly in your posts here. I might even suggest you are too kind and too committed to being fair and seeing the other side and trying not to judge or have an opinion about the ways of others. I am not being judgemental of you in this, rather I am admiring your very generous heart. Here is where I say "but" : But I feel you are being kinder to the other mother than you are to yourself and worse, expecting your little ones to be kinder and more understanding than her little one. It's an invidious situation and I really feel huge empathy for you. Genuine empathy for I had a similar experience.
Briefly: My half sister had two boys, I had three girls. Her eldest was born first, two years older than my first daughter, then her second boy then my second daughter. My youngest was born after a long gap.
We would meet when my mother would invite us all over to see her. We lived further away. I would take a lot of food.
My HS (half sister)'s boys would run riot from the very start, shouting, breaking things, disobedient, swearing, being rude. My mother's attitude: "Boys will be boys." She adored them. I assumed it was because she "just" had us two girls and also because they were my HS's children and she had always made it clear that I was not as loved or as important or as pretty or as good etc as my HS from a different father.
The meetings went on as the children grew up. The boys became more dangerous, hitting the girls who would have bruises, breaking their instruments when they were practising in my old bedroom which the boys had been told not to enter as the girls had imminent exams. When this happened, somehow, although the big boy, about a foot taller, had gone into the room after being told not to, and pushed his cousin to the ground hurting her arm, breaking her instrument - expensive - and causing shock, horror, tears... for some reason, this was turned into my daughter's fault by this boy's mother and my mother - their grandmother, fell in with agreement.
When it was time to leave my mother would parcel up left over food - that I had brought - and hand it to my HS saying how hard it was for her to feed those growing boys.

The unfairness and insults my children received are something I hate myself for to this day. My children now are in their 40s the youngest her 30s. They have children whom they bring up to be polite and do not indulge in the way one sees some children who have so much. I suppose this is "old fashioned" I say it's sensible and the kindest way. Their children are lovely even though I say it as their Granny. We were all together for my 70th this last weekend and the cousins were playing with no arguments and so happily.
What happened to my HS's two boys? They never grew up to have jobs. They have Police records. The eldest, almost 50, has never married, never left home. He is an alcoholic. The younger cannot live at home by Court order, having beaten up his father. He is a drug addict. Their local Police phoned me and advised me never to contact the family and to move so that they cannot trace me. They had made threats on my life when I reported them when they phoned to say they had a gun.
My daughters all have professional level qualifications. Two are full-time mums, running lovely (not "posh") homes, one has an important medical position in a hospital and works part time so as to see her two boys who are sweet and kind and share their things!
Sorry to sound such a boastful Granny but I am telling the truth.
My message - in brief so it will sound a bit harsh, sorry, - is that I wish I had simply said to my children from the beginning that what their cousins were doing was wrong and that we don't do those things because it is not kind. I wish I had not been so middle class and "fair and proper" but had said what I truly believed to my children which was that their half cousins behaved very badly and I was so proud of my girls for the way they coped and that they were kind, did not swear or fight and had good manners since good manners are only about thinking of what is best for others.

Dear Muffin, stick up for your children, gently and kindly, tell them some people are different - we don't know why - and you are so proud of your children because they are kind and they share. Then make sure they have things done fairly. Their toys at their house. Tell Granny, her grandchildren feel slighted by having their pictures removed and those of a badly behaved child put in their place. Tell Granny, her grandchildren do not understand why Granny loves a child who won't share and wets herself on purpose more than she loves them. I'm a Granny of 7 GC and I'm 70. If I am unfair to a little one I want to be told! Straight away! Protect your precious little ones Muffin! They only have you. They come first. Being generous to the newcomer and politically correct won't help your little children. They will feel as if you don't care about their feelings.
Good luck my love. Wish I could speak longer and not be so blunt. You are a good mum. Lots of love, Elle ??

I have written one post on here and I did NOT criticise the OP. I think she has a lot to handle.

I think that the MIL has to account for her actions though.
The OP cannot tell her children why MIL does what she does. Her actions don't really make any sense to anyone not now there is a new kid in the mix with different rules.

I didn't know about the backstory, but I would suggest that this family reduce the time spent at MIL's home.
I think OP's children will benefit from mixing with other people's kids.

The situation described in the opening post is not easy to understand . I cannot relate to it other than I know that the way Isabel is being handled will not work longterm. I know a family where one child has a different parental situation and is treated "better" ie spoilt. That child is now a disturbed teen who is manipulative and yet fragile. Very hard to get on with or even like.
So I think the OP needs to do a lot of thinking as time goes on because things will not sort themselves out.

I don't have a clue what is going on in MIL's brain but her preference for Isabel will not be an asset to Isabel in the long run.
So I would want to advise OP to avoid visiting MIL and find other friends to spend time with. If she is able to.

I am sorry OP because you have a difficult set up here to deal with.

Have you been asked for an opinion /assistance/help.?
Unless you can say yes to any of these then is it any of your business.It would be your business however were you to observe a child that was unhappy or ill / not being cared for then it would be your responsibility to take action in an appropriate manner.

ahh thats so sad isabel is seeking to be a family member.maybe you should talk to isabel mum .....ask her how she would feel by bil adopting isabel;.children often have ructions when a new child is with them maybe isabel has not had the love and comfort of a family home./maybe she used to getting whats she wants being an only child. set some ground rules here. your home .,your rules maybe talk to bil in thr mum ...as for your mil....well i think a drastic talk is wanted..... good luck..

^DH pushed back on me very strongly in a very negative way about this issue around gifts.

I have had some professional input on my own to help me negotiate some relationships better and one of the things I was most strongly advised to do was to not focus on things I felt upset about that MIL did/had done and not to raise them with DH as he responds aggressively.^

Looking back at this thread, this comment you made really concerns me. Not only the aggressive behaviour from DH but that a professional has advised you not to raise issue's. I'm sorry but there's no justification for aggression from your partner because you're upset/hurt by MIL.

I wish I did have fantastic advice for you, I actually think the whole situation is very strange and actually quite toxic.
Imagine visiting a friend on your birthday and being given a gift i.e a book and then as you leave, your friend takes the book from you and tells you it's staying at her house and you can read it when you visit?!!!?

Best of luck going forward because I think you need it.

muffinthemoo
sorry to appear again
I really would like to feel that you are able to say, when Isobel starts some bad behaviour such as that which you describe,
"I am not going to let my children be exposed to this kind of behaviour. Especially when it goes uncorrected. We shall leave now."
I realise the children may not want to leave so prepare them in advance that if Isobel misbehaves you will all leave and go and do something they love - a meal out if it's meal time, or to the park or take something nice like a kite - I am sure you will have good ideas.
As for nobody being permitted to correct Isobel! That is preposterous! I would ignore it. If a bigger child, even one I had never met, pushed my small child off a toy as you describe I would say very sternly to them, "That is unkind! You must not do that! It is X's toy and she is using it. We do not push people off toys."
I cannot understand your BIL actually, he must love her a lot. It would drive me insane seeing a child being created into a monster. I gave you my true experience above. I could give you so many examples of their lives. Once one was expelled from a normal State Comp. His mother thought I would join her in suing the school (I had a position in Education at the time). She never, ever, saw that what the boy did was wrong! It wasn't one incident but a whole long list of things over a long time during which the school kept asking the parents to come and talk to them.
Children who are enabled from toddlers to do as they please, no matter how antisocial, become criminals and leave a huge amount of painfully injured victims in their wake.

Yes play down the wetting and attention seeking behaviour of isobel,the wetting could be due to finding herself in a whole new situation,and indeed the 'naughty' behaviour?(her own mum doesnt seem to understand this?)Also,is isobel allowed to behave this way in her own home,or is her mum stricter there,so she's rebelling when elsewhere?But isobel also may not like these enforced shared visits,with other kids& adults she hardly really knows? Maybe she too would benefit from quieter separate visits while she gets used to all the new people in her life? She's only 3 after all,it must be overwhelming for her if there was previously only she& her mum?are these visits so her mum can have time to herself whilst your BIL takes isobel along?could her mum not go with them and have her own time to herself some other time?i certainly think a different toy arrangement is first-GP's need to give your kids the toys meant for them,to have at home,any that's isobel's own to her,then get in some 'shared' community toys to play with together,just for grannys house,which NONE of them take home.(as suggested,charity shops or jumble sales,or freecycle are places to get some for cheap or free if GP's aren't rich.Then tackle the photo situation.tell her in no uncertain terms you find the removal of your kids photos hurtful and confusing,to you & your hubby,and also to your children,and get her to explain why she's done so.Take it from there.Tell your children yes they have to share their grandparents now with isobel as she has none of her own and yes as their uncle is now 'being like a daddy' to isobel,that makes their GP's like grandparents to isobel also.anything other than that they won't understand at so young an age.

Sarahhellenwhitney,it IS muffins buisness if it involves the treatment (by isobel)(and by their gran) of her own children!

I suspect that Muffin has tried to assert herself with her MIL and has found that it just makes life uncomfortable all around. If her husband won't back her, it puts her in an invidious position especially as she has her hands full with a young baby and I don't blame her at all for not wanting to cause confrontation from any quarter.
Muffin, your problem is going to be how you are open and honest with your children without them repeating you in front of MIL and DH! I think we all have to, at some stage, to say to our children that parents are like teachers and they all have slightly different ways of doing things. For the wetting in the wrong place, taking off clothes, etc., you just say that they know a different way of doing things that makes them more acceptable in polite company. Answers about family can be run along the lines of, "Legally they are not family until BIL marries Isabel's mother but we're happy to have her as family before that happens." I think with the toys that MIL insists upon keeping can be handled in several ways. You can either get them a little something extra that they take home and say something like, "This is to make it the same as Isobel," in front of MIL and hope she gets the message. Or you can suggest that the children ask MIL for her reasons. Alternatively, just explain that some people have quirky ideas and this is just one of them. It may be that MIL doesn't keep Isobel's presents because she isn't family so may never see her again if the relationship goes south.
It is good to get children understanding that all parents do things differently. It will hold you in good stead when they are teenagers and everybody else's parents let them stay out til all hours!
May I suggest that you give your MIL a framed family photo for Christmas and redress the balance. Meanwhile, just dismiss the questions about photos with an explanation that a change is good as a rest and the good thing about photos is that there are normally new ones hung to ring the changes.
None of these solutions will change the basic problem, your MIL and husband, but at least your children's fears/worries can be allayed for the short term. If I am honest, I suspect that you will never change their attitudes towards you but only you will know when you have had enough.

Blended families can be tricky. I speak from experience! I am always honest with my grandchildren and answer any questions. Children are very receptive and adaptable on the whole.
I would advise not to get involved and never pass any judgment that involves adult relationships, parenting or anything else! And comparing children and how they behave is not a good idea.
Regarding Isabel, she is going through a transition and 3 year old are always testing the boundaries. My grandson ( now 5), has been very difficult over the past 2 years, and I know people have judged his behaviour. However, he is a lovely little boy and is now much improved He just needed time and understanding. My granddaughter (3) was forever wetting herself, but is now completely dry. Just be patient and worry less!

Sadly it does seem kids who are allowed to run riot as they please do end up badly off in later life, one of my elder children took under her wing the child of her partner (result of a one-night stand he had before my daughter even knew him)at about 3,he used to come weekends etc,my daughter treated him like her own child,then when they had their own kids together,treated them all same,then after awhile childs 'real' mum didn't send him for a bit,let him run wild on estate where they lived,doing as he pleased,staying out with older kids,(age about 8/9)! He got in trouble,went to live full time with my daughter&his dad,was settling down living a real family life,we as a whole family,treated him same as all other kids in our family,he WAS part of all our family,then he started visiting his mum.'bad' behaviour started again.he went back to live with his mum full time,lost contact with his dad(through no fault of his dads) now he's in a young offenders institution.its such a shame for that poor young boy,as when he was around our family he was such a good kid!His own mother has a lot to answer for!(I've brought up 7 kids,mostly on my own,and they all have good manners,and either respectable jobs or are in study at college/uni.) I now have GC in differing ages,(older to younger) and all of them know how to behave.Its how you're brought up that makes the difference.

Surely when you give a child a present, it becomes theirs to take home and to have as their own. The only odd thing I find in your original post is the toy issue. Why does your MIL give presents but then expect to keep them? Otherwise I see no reason at all for anything else in the situation to be 'tricky'. It's just family life - the usual mixture of stuff. My grandchildren call my husband and I by our first names - if Isobel is doing the same re your BIL and your MIL, that's surely OK, isn't it? I don't get the need for 'eggshells' at all.

muffinthemoo
(Looks like my referencing - stuff I said I'd get on with - will have to wait a bit!)
You said:
"I am sorry if my tone appears defensive."
I'm aware that you are trying hard to not offend anyone, Muffin. I am feeling more and more concerned for you. It feels as if (and I stress 'feels' since I only have as much info as we have here) you have a difficult life. I would go so far as to say a life in which you have to deal with a DH who "responds aggressively." and a MIL who does things which "I felt upset about", but which you have been told you cannot talk about or raise with the one from whom we would usually seek support - our DH - because he responds aggressively.

You are treading on eggshells in your home. Your husband cannot be consulted about his mother's austere rulings over the children's possessions. Both your husband and his mother combine in a considerable force to rule in your life and your children's lives about how you should live. Now a situation of conflict has arisen in which your children are being treated most unfairly and are unable to understand why. You have your hands tied by these threatening people about how to deal with the situation. You can't do what a normal person would do. That is you can't just talk to them about the unfairness. This is because they are not normal people. To become aggressive when your wife asks you about the behaviour of his mother in keeping his children's presents at her house but letting a new child take the children's toys away, is not normal. The person who advised you not to raise it with him might have been right but it was not the permanent answer to your problematic situation at home. He is not reasonable to become aggressive about an issue where his mother is hurting his children.

On top of this, the controlling behaviour of the Grandmother suggests DH's upbringing was anything but straightforward. The two of them are hardly a warm and loving, caring and fair-minded pair. Poor Muffin! To be told keep your mouth shut and don't upset them makes it sound like your responsibility when actually it is their personalities that are at the root of the problem.

I would like to urge you to get more advice. The first counsellor we find is not always the one best suited to our situation or to us. You deserve support. You are trying so hard not to upset anybody, it shows in so much of what you write here. You are so aware of not infringing the rights of others, I fear you have forgotten that you and your children have rights too.

Dear Muffin, please ask for Counselling. If it means suffering in silence for a while waiting to get a Counsellor, so be it. But regarding the children, I can only say, that my experience with my own is that I regret I did not say, from when they were as young as 2 or 3 onwards, something like, "I don't know why Granny does that with your cousins (Or Isabel) and I don't think it's fair. I am so proud of you because you behave like good and kind people. If Granny lets your things get broken/taken by Isobel, I will try and replace them. This is because I do not agree that your things should be given away by Granny. Perhaps she has special reasons that she has to keep secret at the moment. But I love you and you deserve all your things."
I know when my children were young they did not understand why their cousins were favoured for being cruel, rough and mean. I wish I had simply said to them that I did not like what their cousins did and that what they did was wrong.
My husband didn't support me in anything. He was a covert or passive narcissist.
I will be thinking of you Muffinthemoo. Try to feel more confident. It is obvious that you are a good and kind person. Maybe people take advantage of you? If it is possible, could you cut down on the visits to their Granny?

Having read it yet again, I would like you somehow to get across to your children a shared secret joke that you all know that "Granny is a bit weird" and that "her weird idea is that when she gives a present to you, it still belongs to her!! But if you say anything she will get angry so you keep this a secret!" If you can afford to make it up to them by having a little present to unwrap after going to Granny's and having to relinquish whatever she un-gave them, they may get some comfort from knowing that they do get something that is really for themselves after seeing this weird granny!

Sending you lots of love Muffin! Be bold and brave and believe in yourself! ??(tractors can go anywhere!)

I would just say something like I'm sorry darling I isn't know, perhaps it would be best to ask Grandma. You can't be expected to answer for your Mil. And you be will being honest to your children which is important.

I really feel for you Muffin. This does sound a tricky situation to me. It wouldn't be if your own children hadn't picked up on why this little girl is being allowed to behave in, frankly a rather naughty fashion. If it were not for that you could just ignore it. As it is, you've genuinely asked for help and advice and been met with citicism and unhelpful remarks from a few GNs.
I'm afraid, I don't have any constructive advice to give, except to say to MIL that perhaps in future any gifts given to the children should be allowed to go home with the children. She could keep a few toys at her house to be played with by all.
I'd also ask about the family photos, that smacks of either favouritism or perhaps she's just trying too hard to welcome the newcomers into the family, at the expenses of others feelings.
Obviously don't voice this to her!
Other than that, try to grit your teeth and be as jolly and welcoming as usual and hope this little girl learns a few manners by osmosis.
I don't agree with those who say she's "only three" and therefore this is normal for her age. Even three year olds can learn, in fact they're veritable sponges and soak up everything.
Good luck, I'm a bit old school myself and have three well adjusted, kind, well mannered, happy adult children to show for it.

I certainly wouldn't be trying to explain the ins and outs of everyone else's relationships with children.

The brother in laws (weird) set up with Isobels mum and whether they're married or not is their own business.

Dee1012. I agree. I think this gives insight into a very difficult situation in which Muffin has been forced, I would say coerced. She has been told to withdraw from having her own opinion and worse from feeling her own feelings in order to give in to two aggressive and controlling bullies. I am extremely worried for her. That she couches everything in an apologetic caveat of trying not to offend us says so much. She is treading on eggshells, even here on the thread. It is a big sign of being in a coercive and controlling relationship. The "advice" she was given may have been well intended in trying to avoid Muffin being faced with violence, but it is very poor Counselling in that it does not address the situation at all and leaves her and the children with a threatening man. It also tells her to alter her behaviour, which is actually what the Law looks out for in recognising coercive behaviour: "actions which cause the victim to change their way of living." It also specifies as an example that the victim has a "fear that violence will be used against them" which is why Muffin does not ask her DH about his mother's actions.
The government website is:
assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/482528/Controlling_or_coercive_behaviour_-_statutory_guidance.pdf

Oh goodness me feel for you Muffin you sound like a great lady and doing your best with your parenting skills, what a difficult situation poor Isabell wetting herself sounds as though she’s mixed up bless her heart, your MIL sounds very odd, I would have to ask the MIL why she has taken the photos of your children down that to me is a smack in the face

Muffin, the thing that struck me most about your post is how you're bending over backwards not to be judgemental and not to upset anyone involved. But now it's you that's having all the stress and that can't be right.
If your main issue is with your children's questions then what's wrong with telling them the truth, even if it's 'I don't know'? It's not your responsibility to answer for anyone else's behaviour and you shouldn't have to be in a position where you have to make excuses for other people.
As others have said, you could explain to your children that everyone parents differently and have different priorities and that the way you parent might be different to other people's way, but you believe it's the best way for you and yours.

I can understand that Isobel is the "new girl" and therefore getting used to a new group of people. But I fear people here are urging her to be treated too gently even at the cost of the other children and her own welfare. She is tough enough to be told not to push a 1 year old off a toy. Indeed I would say that not to tell her that is not in her best interests. She will not find it too much if she is told not to do something and why not. At three children tend to play alongside each other more than with each other. Also people are speaking as if Isobel has not been to a play group/nursery school at all. I would have thought she attends something and has been in day-care probably, or how has her mother managed for money? Usually a single mother has a job.
Anyway, since these are imponderables, the way Muffin speaks about the situation of them meeting at her MIL's suggests that it is not new at this stage and that her children and Isobel have been together at MIL's for quite a few visits. I would also like to reiterate, if a 3yr old pushed a 1yr old off a off a ride on toy, I would certainly speak to the 3yr old, quietly and firmly about why we do not do that. I ran a play group years ago and am a Qualified Teacher among other things I did as well as Teaching. I think it is actually not kind to the errant child to let them upset other children without putting it right. They will wonder why they have no friends and will become increasingly aggressive.
What a terrible situation for Muffin! Maybe her BIL needs to discuss with his new Partner the need for him to be able to deal with Isobel's behaviour especially when she is absent. It isn't just his problem, it affects everybody with whom Isabel comes into contact. No little child can go out unsupervised and this is what it amounts to when Isobel's mother is absent, and when she is present too from what Muffin tells us!