Daughter in law harassing parents and husband

Respected Sir/Madam, My brother got married 5 yrs ago and right from their honeymoon time my sister in law had fights on small points. Being just married we always thought that they are young and situation will be under control. But what is wrong with my sister in law we are not able to figure out. As soon as she became pregnant within few months she wanted to abort the child. Some how all the family members made her understand about her wrong decision and child was born. During her pregnancy she was not at all in contact with her husband and in law. She stayed at her mom's place After the birth of child she came back and kept my parents and brother to help her out on day to day basis. Every now and then she keeps on fighting with them. In one of such incidence one day she went to pick her kid from school and without informing anyone at home went to her parents house. My parents were so worried about where she must be and kept on searching her. She has started giving such mental torture to my parents and brother. She will always fight with my brother even if my parents are out of town. She will not make Tiffin for him. She will not allow her son to mingle with my parents and brother. She just keeps on giving metal torture My mom and dad both have gone through hospitalization due to health issues even in such situation she will definitely fight on the day of their discharge My brother has to go to job and after coming back home he has help her in her household chore Even during his weekly off he has to be under her control. Even after facing all these things they just kept on let going off and ignoring her behaviour But now she wants to get separate from my brother and every time she keeps on blackmailing that she will take her son's LC and move at her mother's house. We still want this marriage to go on But if she decides to move out and files for divorce Is she eligible to get any share in the house co-owned by my brother and father. Can we make a gift deed any transfer the house on my mother's name What about the child's coustody What about alimony as my brother is sole breadearner he has home loan liability salary is around 30k and even my parents are wholly dependent on him their medication exp is around 5k per month We have asked her to go for counselling but she doesn't agree on any points Secondly seeing her behaviour it feels that she has some psychological problem is there any way out to prove it Please help now even my brother is fed up of her