Is this normal

I feel sorry for the children being mixed up in all these relationships. It's up to the parents to decide what happens no matter how wrong or unjust you may feel it is.

Loads of good advice already given. I think the underlying issue maybe jealousy I’ve witnessed this when another family are introduced to the GC. I have a friend who’s ex is in your sons position and she’s moved miles away with the children to stop them getting involved with ex partners family, it was jealousy behind it.

The needs of the children come first, they need to see their parents, both of them, at Christmas.

In the cause of stability, that would be my priority for the children.

Adults can wait.

Depends how new the new relationship is. No parent should be introducing children to new partners in the first 6 months at least, IMO. Possibly not even for as long as the first year.

If a parent has a string of partners, nothing wrong with it, but the children need the stability of only being introduced once it looks as if it will be a permanent relationship.

Is this a concern of the childrens father? If so, I think he is entirely reasonable. Can't she go off to see her new blokes family, leaving the children either with their dad, or with your family? I can't imagine the children will be thrilled to spend the holiday with people that are little more than strangers.

And of course the father gets a say in who HIS children see when he is with your daughter. He doesn't stop being their dad just because they're not together anymore.

If he were to talk them someone inappropriate, presumably your DD would have a say in whether she thought it was appropriate or not.

Sorry, typo, who HIS children see when they are with your daughter.

There is no dispute over who has them which day. The children who are 8 and 11 will definitely be consulted as to which parent they are with.
All I was asking was your opinions on their father dictating who they see when they are with mum.

.....and yes, they have been separated for a while. DD just trying to get the papers signed.
Just to add he has a new partner too , whom the boys see

i don't think he can say anything about where she takes them, with whom etc on her days to have the boys, unless there is some abuse involved.
that's the reality of splitting up.
others will know more.
however we might think it is not ideal, all that is subjective, like ideas about diet, lifestyle, religious practice or not, he does not have a veto.
nor her with his activities/ associates when he has them.
they should each do what is best for the boys, of course, but each has as much right as the other to decide what that means in practice.

Our family is one gets Christmas Eve/morning and other gets Christmas lunch/night. Next year it's other way round.

This doesn't seem to be about Christmas arrangements but more to do with controlling who the ex-wife can introduce his children to. The short answer is he can't. Unless there are safety reasons, when your DD has the children, it is up to her who they see. Equally, when your SIL has them, she has no say. He could introduce them to a different woman each time he had them but unless the children were adversely affected there is nothing she can do.
This is something that women often use to avoid giving the Father access and use all sorts of "rules" to control the situation. The courts do not allow this but, often, men don't realise this. Now, it may be that it might be comforting for the absent parent to get to know the people in their children's life but it isn't an absolute right. Your daughter, assuming she is a responsible parent, will be deemed by the court to be able to make the right decisions for the children and the same for the father. There are a few areas where both parents are expected to come to an agreement about like the school children will attend and if they can't, the Court will make the decision.

I wonder whether your daughters soon to be ex was controlling while they were together and can't lose the habit now that they are separated.

How long has ex been with his partner?

How long has DD been with her new partner?

Message withdrawn at poster's request.

I do feel for the children as they can be used as a kind of bargaining tool, with more often than not dad being the one side lined. However, I am sure in this they want what's best for the children. It's between just those two to decide what's best. I don't know the father but maybe he is just voicing a genuine concern and not being controlling, whatever it is.