Very long...need guidance.

My husband has very little contact with his parents, they were/are verbally, emotionally, and at times, physically abusive toward him. When he got out of college, got a job, and married me( of whom they do not approve because...I'm fat...really that's why) they turned their attention to his little sister. My sister in law is 17 years old and lives in a small town in Georgia. They told her she could not date the boy she was currently seeing because they did not want her to turn out like my husband( dating below their class). His sister stopped seeing him, but still texted and spoke to him on the phone. Upon learning of this they threw her in a mental institution. She was there for 3 days and was released because there was nothing wrong with her. Her mother started berating her daily, telling her she was worthless and a whore and would never amount to anything. My sister in law took pictures of any abuse they did to her to show a case worker, if she could get one ( they would not allow her alone time, and her mother is the principal of another school in town so she knows all the teachers). They found the pictures, deleted them and put her in a different hospital. She was released the next day. She ran away to her exboyfriends(who she then started dating agaib) and lived with him and his family for two weeks( they knew where she was, she left a note). After cheerleading practice one night her Aunt(who works at her school) told her she left something in the locker room. Her aunt escorted her there and she was ambushed and kidnapped and brought back to the parents home. They broke her garage door opener, took her keys and her phone and took her to the same mental facility she had been in. She got released 3 days later. After being home for a week her dad broke her phone and ipad so she could not contact her ex anymore.

Fearing for her safety, my husband bought her a temporary one to use in case of emergencies. They found the phone and put her back in a mental institution claiming she was suicidal. When she got out 3 days later and her parents were told that this had to stop because there's nothing wrong with her, they dropped her off at the boyfriends house and texted his mother saying, "she's your problem now". They didn't give her any clothes or money. That was right before Thanksgiving. Fast forward to now, her mother is withholding all of her scholarship forms and her ADD medication unless she comes alone to their house to get them.

We have tried everything to help. His parents are very very high up in this small community. My husband's uncle is the chief of police and my husband's mom has taught/been the principal of just about everyone in town.

She can't get a job because all the owners know her parents. No teachers will get involved and any DCFS case that gets opened...magically gets closed. We're at our breaking point (we also live 2 hours away so not much we can do). We can't see her because we live in Florida and if she crosses state lines his parents said they will have her boyfriend and my husband arrested for taking a minor across state lines. They don't want her, but won't let her go.

Is there anything we can do??? Any advice will help.