Why are you enabling her to stay out all night without any repercussions? Whatever you decide to do, is this the way you want to live until things are finalized?
That's incredibly disrespectful, and a horrible example for your children. Personally, I'd tell her the next time she's out past, say, 1am, to not bother coming home, and I'd turn all the lights out, put the alarm system on, and even change the locks.
