A definite no from me. When you went as a couple last year you kowtowed to his parents and let your child get overtired and uncomfortable. I understand why as they sound very overbearing. This year he is proposing half the number of people attempt to stand up to them and advocate for your child’s needs. Not going to happen is it?
The way I see it they’ll either be tutting and getting annoyed with you or with your dh. When children are little, plans tend to cater around them because of their needs. They don’t want to do this which does make me wonder what they were like as parents.
As you say you’ve proposed they come over to you and you all go on holiday. This sounds like a really good plan. I assume they are retired. So why is it always you going over to see a retired couple when one or both of you work and have a young family? They chose to move away, have time on their hands and possibly a larger disposable income, so they should be willing to come back to see you too. Bottom line of it’s that important to see their child, they’d come over.
I think your husband is trying to seek approval and love from people, who are very self centred otherwise this plan wouldn’t even be a possibility. If you were able to ask your ds and he understood what was happening to him, you know he’d say no.
Dh would like to take dd to see his family alone, he’s foreign. I know he would do a sterling job of looking after her. I always said no when she was younger as I knew she wouldn’t cope well with the separation from me. She had separation anxiety, which got a lot better between ages 7 and 8 but not completely fixed. (She worries about me as I’m chronically ill). Now at 10 she won’t go with him alone. Fil is a nice man. But very set in his ways and has no idea of how to connect to dd. He doesn’t come over anymore due to age. Dh goes sometimes alone and we holiday close to his house once a year and see him then. It works well for us as dh can do stuff with his dad alone, which he wouldn’t get to do with us around.
Suggest your dh goes for a long weekend. They can do adult stuff together. It sounds like your in-laws don’t want to do kiddy stuff. So why the eagerness to take your ds? I don’t get it.