In reading the story, the largest problem seems to be the kids' attitudes. Can you imagine being in your mother's face like that? Yes, I'm in your bed. Yes, I'm gonna have sex. Call the police, I dare ya.
What do you do with a kid like that? Now the problem may be that the mother is a wimpy authority and has caused her own problems. But the girl is staying out all night, was already on probation for who knows what, something needs to be done.