No wonder your daughter is a bully. Her parent is equally as bad for not understanding the severity of bullying. You are totally clueless and out of touch or you are a troll.
You have no cause to sue anyone.
Teach your daughter to be a better person because she is the one with the mental issues. You see, bullies are really very insecure people who have no self worth, so they pick on others to temporarily boost their weak self esteem. But, because the bullying only gives your daughter a momentarily sense of superiority, she has to do it over and over to pad her weak ego.
So, you see dear, your daughter is the one with the huge problem. You being one of them. Teach your daughter to be a compassionate person and do things to help her with her weak self esteem. It is girls like her who end up with horrible men. It is not too late to save her.