As I understand it, your DH has one or other of his DGC round on alternate Sundays (so just one weekend day out of four) to take some of the pressure off his son’s very new little family unit. Good on him, he sounds like a lovely, kind man, and no doubt he enjoys the chance to spend time with his grandchild. They’ll be at school soon (the 4 year old from tomorrow, I assume), so less chance for him to see them during the week while you’re not around. You’ve made your feelings clear to him, and he doesn’t expect you to help, but you still feel resentful. He’s already suggested you go out while the child is there, so if you want to watch a film why not go to the pictures? Or can’t you arrange to meet up with friends on those days? It’d be lovely if you could make the effort to spend a little time helping him out and getting to know the children who are, after all, part of your extended family, but if you don’t want to, you don’t have to. Are the children at yours all day, or is it just for a few hours?