When you are separated, don't you set a fixed schedule of who gets the kids and when? \
If so, I would wonder if you should say no. From what I've read, stability is important. Going with her to 'party' at her age seems off.
I believe you should care if you have evidence to believe what is going on is bad for them - they are your daughters. If it is just a movie, then maybe letting go is fine.
