My ex used to threaten 50% custody (“so I don’t have to pay you”). On the advice of a counsellor, I called his bluff and sent him a sample schedule. Never heard about it again.
The reason I didn’t want that is that I knew it would not be best for the DC, because of his behaviour with them. But he knew the threat worried me, that is why he was using it.
I’ve also accepted that I will not ask him for back up childcare with illness etc (and I wish we had an amicable relationship where we could co-parent like that, I really do. But he makes it impossible.)
It just gives him an opportunity to verbally attack. He says no anyway - always an excuse. If he ever did help, it would be held over me forever as an example of how he is flexible and I am not !
I have also learned not to give him an inch - agreeing for the children to come back early on his weekend for example, because he “feels ill”. For some reason, being reasonable and flexible in that way seems to trigger worse behaviour from him, no idea why.
What @Hidingtonothing said, I totally agree with, although it was so hard to come to terms with because it didn’t seem fair. I’ve had to learn to ask other people.
I’ve also realised that I need to pretend the opposite of what I want - so in your case, if he asked to have DC more, I would say “that’s great, thanks, gives me a chance to get to a yoga class!” or something similar. Then he would stop, because of not getting the reaction he wanted (arguments/drama/any engagement from me)
He recently got DS’s haircut with no discussion. From longish and curly to ridiculously short - almost shaved. I didn’t recognise him at first when I picked him up from school 😞
But, I took a deep breath, reminded myself it will grow and just told DS he looked lovely.
My ex would have known how much that would upset me, and would have loved an angry phone call from me. So, I gave him nothing. No response or communication about it. It means it is less likely to happen again and it means I am not giving my energy or power away to him.