Divorce

My sister in law got married approximately a year ago. She later realized that the qualifications claimed by the groom before marriage were fake and that man doesnt even know how to read properly. The girl is well qualified MBA. 2-3 months after marriage, they gradually started harassing her with financial demands or dowry. She was abused every now and then. she was mentally as well as physically assaulted. She was not allowed to talk to her relatives or even parents. She could manage to get a good job in a reputed company but then she was not allowed to keep her own bank account and also was given a very meager amount for daily expenditure. She could somehow manage to escape from her marital home and narrated all to her parents. She and her parents are willing a legal separation and wish to recover all their expenditure on marriage from them. She is living with her parents for last 2 months. They already have 2 meetings with the people from the groom's side and a lot of bargaining about the money to be recovered is being done. Please guide the way ahead as we wish to teach them a lesson too so that they cannot do the same with some other family.