I would tell her to make an appt. with her pediatrician and see what kinds of testing she recommends getting done. I would also call a lawyer afterwards and ask if she would get in trouble going ahead with the tests against her father's wishes. If she has sole custody, I would think that she doesn't need the father's consent. I mean, if the child were physically sick, surely she's not expected to have his permission for bloodwork? If I were your friend, I would have my child evaluated in a hospital. She would be monitored 24/7 and they'd be able to determine the best solution as far as meds go for her. In the meantime, she may want to allow her to stay with her dad, just to keep the other kids safe. It would be hard, but she may not have a choice. The only other thing I can think of is to give the kids a whistle or something that makes noise, and if she starts to go after them, have them blow the whistle so you can come running, but that sounds too sad for kids to have to do!! I have a neice who was abusive to other kids, and they admitted her to a place in Plymouth. When she came out two weeks later, she was a much happier kid. She was diagnosed as depressed and bi polar.