De-lurking to say...
My parents live 10 minutes drive away from us. I'm an only child, who is a single mother of a teenager (almost adult) DD and a pre-teen DS (who who has mild AS). DS goes to his father's every other Saturday (DD refuses point blank to get involved, although she knows my ex, his wife, his family all love her and will always be there for her...). DS, on the other hand, goes because he wants to, but at the same time, he doesn't want to. His behaviour is abysmal building up to, and coming down from the trips. Consequently, because I got tired of having to deal with the every single Sunday vists to my parents, where, nine times out of ten, I was being patronised and criticized by my parents about DS's attitude/behaviour (they refuse point blank to acknowledge that his brain is wired slightly differently to other people's), I said that we were only going to visit them every other Sunday on the weekend where DS wasn't at his Dad's.
Please note, that both of my parents have developed the habit of randomly turning up on my doorstep without invitation, staying for several hours (whether it's convenient or not), and treating me as though I'm still 3 years old... in front of my children. Also, that when my grandparents were still alive, both of my parents complained - bitterly, and at length - about us "having" to visit them every weekend. Yet... they used to dump me on them every other weekend from the age of a year old (my parents don't "babysit" my children, and the one time I've asked them to, have actually had a go at me for "needing a break"). I'm still working on boundaries with my parents, who are so set in their ways that they actually seem to be refusing to grasp that my family (ie, the children and myself) need space. We weren't a close family to start off with, either, so I don't understand why they're so upset about my "we'll visit your house every other Sunday as opposed to every Sunday". They have no clue that I graduated university, for example (I was a mature student, who paid her own way without their "help", with a toddler DD in tow). The main turning point for me, though was when I realised that they were beginning to treat DD the same way they were treating me.
My children are happier for the Sundays we get "off", together. I am, too. It means that we can catch up on our family time, albeit whilst DS is "coming down" from his time with my ex (who is, actually, lovely and a great Dad... he's just not accepting of the fact that DS likes routines, and boundaries, etc., etc.). We've worked it so that the Sundays after the Saturdays DS spends with his Dad, we have together at home, so that he has the time and space to re-establish his comfort zone, cuddle on the sofa, walk the dog... generally relax without having to be dragged out anywhere. DD, on the other hand, is at college full time and works all day on a Saturday. Her only day "off" (although she's also doing college homework) is a Sunday. My parents won't allow her to take her college work to do at their house. At all...
Stick to your guns. Please, learn from my mistake. Don't let your family start to crumble the way mine did.
(Incidentally, will we be there for their wills being read? I cannot, and will not speak for DD or DS... but I know that I won't be. I don't want anything from my parents. At all. I never have; I never will. They barely raised me, they don't know me at all, and I will continue to distance myself from them.)