I don't think she is being abused. Why would a 7 year old girl be obsessed with ?

Honestly, just becasue she asked her mother what the male anatomy looks like, doesn't mean she doesn't already have firsthand experience. It may be her way of trying to get her mother's attention to the matter. All signs point toward ual abuse. That is not normal behavior for a girl that age, even if she was going trough premature puberty. Even if she hasn't been physically molested, she has definitely been exposed to things that I would consider abuse. All that being said, I have no idea what you can do for her, other than pray for her well-being and report to the "officials". If the parents have seen the signs (obviously) and aren't already doing something about it, I doubt bringing it up to them would do any good. Her school guidance office may be the best place to start.