Ex decided to let me know, at midnight last night, that he wanted the kids from 11am today to sometime on Sunday for a family party/sleepover.
They won't do overnights with him, especially dd1. Dd2 didn't want to sleepover because she didn't want to be away from dd1, but would go to the party.
Ex then started his usual games of picking at dd1 and myself, blaming us for dd2 not wanting to stay overnight with him. Dd1 still wanted to to go. I allowed her to go, against my better judgement, but made her aware I'd come and collect her if she wanted to come home before ex did.
When she got to his, he started on her all the more, knowing this would result in a tantrum allowing him to tell her she couldn't go to the party for misbehaviour and leaving him with dd2, so he could stay play the doting father for his family.
It worked. Dd1 walked out in tears. What he wasn't banking on was dd2 following her because "I don't want to go to a party where my sister is not allowed and I don't want to go a party with someone who bullies my sister"
He's had to apologise to both of them.