partners and new grandchildren

Ohh I do feel for you, put aside what he wants & what your daughter wants, what do YOU want, how much time do You want to spend babysitting etcetc, once a month is not IMO unreasonable by any stretch of imagination.
I know it’s a difficult situation but do this for you for how it suits you & let those who care about you show it by being supportive & reasonable , best wishes

This situation would be non-negotiable with me, he would either have to like it or lump it.
You are going to have to be more firm with him about your wishes gigigem.
It's not unreasonable, in fact it's normal, for you to want to see your Daughter and family and if they have become used to staying over before the baby, it will seem strange why they are not welcome to stay now.
Asking you to have the baby overnight once a month is not over the top either and I should imagine that you would love it.
It's ok for him to want his space and solitude and he can have that for most of the time but should accept that you like to see your family.
Is there any way that he could go somewhere when the baby stays over? Does he like fishing? Or bird watching?
If he really digs his heels in, could you look after the baby at your Daughters house?

I can't add anything to Bridgeit's post. Well said.

I don’t think it’s at all unreasonable to babysit once a month blimey that’s nothing is it? so from that point of view I think your partner is being very unreasonable Why do they stay the night when they visit do they live a good way away and how often are these overnight visits ?
As your partner walked your daughter part way down the aisle he must be very fond of her, so it sounds as if the baby is his problem Does he not like small children or is he jealous of your attention ? I guess from your story it’s not clear how much time and attention you give to your daughter and baby so it’s hard to say who’s being unreasonable or if it’s just a difference of a way of life you in which case you may both have to compromise

I agree with BlueBelle's post, I'm not sure why its a problem now as he is clearly fond of your daughter.

I have to say he does sound as though he does not want anything to interfere with his life. Babysitting once a month is a reasonable amount, I don't think that anyone would find that excessive. You are going to have to put your foot down if you want to maintain a good relationship with your daughter and son in law. Is your partner willing to compromise? Does he know how important this is for you?

Well, I tend to sympathise with the partner.
I think he may just be coming to the realisation that this is an ongoing situation, not one that would all but end when the children had families of their own.

May I ask how old you both are? I have 8 GCs ranging from 3 - 25. DH was fine with the eldest 4 when they came to stay, was happy to take them out and join in activities with them. He is not so happy with the 4 youngest ones. He finds it very tiring and disruptive. He loves them to bits and they are well behaved and fun but, as he has got older, he needs his routine.

Whereas I actively invited the older ones, I wait to be asked to babysit the younger ones. Sometimes I suggest that I stay over with them instead of them coming to us. I don’t tell them it is because their dad finds it too much.

I can see both sides here and I think a compromise needs to be worked out. It is his home as well, but you are not his property that he can decide who you spend time with.

Once a month? A whole twelve times a year?

I think he is being a bit unreasonable here unless there are some other factors (eg health, disability) not mentioned.

I think the term ‘blended’ families sums up the hidden constraints. It can’t be easy.

I suppose all you can do is reassure your daughter and son in law that you would definitely like more contact and that in the meantime you’re going to discuss the issue with your boyfriend to see if you can sort something out that suits you and soothes him.
Good luck.