My ex has children by three women. Me - two uni age. Ex-wife - 3 kids 12-9. Ex-GF - 2 kids 7 & 5. For context his ex-wife and ex-GF hate each other.
During the summer my girls had a few days where they had all 5 half-siblings over to visit at our house. This was nothing to do with me in terms of childcare or anything (this is relevant). The girls did it all as they wanted to spend time with their siblings. I was happy for them to do so.
Ex's parents are lovely people. They have a wonderful relationship with my girls that they made the effort to cultivate (by asking me for time with them) when their son wasn't bothered. They haven't spoken to him for around 7 years. They have always sent presents and made efforts with all of the children. Ex-GF has allowed contact since she split with ex so they have a good relationship with those two children. Ex-wife never has and is still reluctant.
Ex-wife admits herself that she was "horrible" to my girls and, frankly, I'll never forgive that.
Ex-wife has said that her children are asking to see their half-siblings so has asked me to facilitate the 5 younger children meeting at my house while the girls are away at uni, rather than them having to wait until the holidays.
Their grandparents have said numerous times that they'd have all the children at theirs, but ex-wife is reluctant to do that.
Apparently I'm now 'nasty and mean' because I've said no to giving up my saturday mornings once every 6 weeks to facilitate this.
I've got three children at home still. One of whom is severely disabled with a life-limiting health condition. Literally the only thing I did for the children all coming round in the summer was to have my children put away any special/new toys that they didn't want played with. That's it. On one occasion I wasn't even here!
I'm a people pleaser 99% of the time, but I'm trying to get better, but now because it's children involved I'm doubting myself. I just don't want to spend a morning with 5 extra children. ex-MIL would love to have them all - and she, exFIL and exSIL are all perfectly capable of looking after them.