the first thing I would recommend for the parents is to make sure they try to talk to her, and have them talk to her in an understanding tone, saying they know that something is going on, and they're not there to just, but rather there to help. I also recommend if that doesn't work, let her know that she can speak to a therapist in private without people at school knowing.
I recognize this as I was that girl for a while, and I know how it feels. that is what I wished someone did for me. I tried to speak to my mother and she told me to toughen up,that's it. I eventually ended up seeing a therapist in private and it helped SO much. 3 years later and I still remember it all, and it's going extremely well, as I still get to be happier and happier.