would appreciate some advice please!!!?

You need a good lawyer,and if you have concrete evidence on the mother abusing those girls start by calling the police,social service,there dr can document things . Take pictures, keep a log but you need to start off by getting police records going. You should see if he can gain full custody then ask the courts a guardian light for the girls,if they can talk then you need to get things going asap try to ask the mom if the girls can stay for a few more days until you get a hold of attorney. But don't tip your hat,or take the kids keep this as easy as you can for the kids. I hope things work out for everyone,

You can't really do anything. No matter how much you care, the courts don't consider you at all. All he can do is document things and go back to court. Getting a good lawyer can make a tremendous difference as well. One thing he may want to do is try to get more visitation at first, but a good lawyer will give better advice for his situation than anyone on here can. If the kids are a priority, it will be worth it to pay for the lawyer.

You can't do anything. They are not your kids. And since you don't give any details, there is no advice anyone can give you for what your boyfriend could do either.