Urgent (family and property) issue

Hi sir, I would like to explain my mother In-law’s family issue... Please advise me for taking decision on her issue. my father in law had two wife’s due to his first wife doesn’t have children’s at the moment then he decided to get married his first wife sister with all family members support including his first wife. After his second marriage both wife’s got pregnant... finally first wife had 2 children’s (1 girl and 1 boy) and second wife had 3 children’s (3 girls) and all are staying in single home and passing days smoothly… but when my father in law passed away … then first wife giving troubles to his sister (second wife) she is always telling that your are not legal wife. But second wife has all proofs. My father in law has 4.5 acres land along with 12 plats apartment including living home…. both wife’s are continuing to stay together in the same home after my father in law pass away. One find day both (wife’s) are decided that, in this situation they will not finish there all daughter’s wedding without money... So they diced to give ½ acres (50 cents) land to each daughter and same they completed registration and property documents also given to their daughters. Finally all their daughters got married without any problem. Now only son is waiting for his marriage (First wife son) First wife son completed registration of property to his name including home and land of 2.5 acre’s) without explaining to his step mother. He given only 7 cents land to his step mother. When they went for property registration to his son, he promised that both mothers are equal (own mother and step mother) and I will take any decision after both mothers are accepted only. But after registration completed he is not respecting to his step mother... First mother and her daughter and son not considering step mother and her daughters and son in laws. They treating her like slaves. They are not giving single rupee to his step mother even if she is not feeling well and also she faced lot of issues with from first wife family side. Due to this situation she decided to come out from the house and decided to go to court for judgment... Currently she came out from home and staying in her daughter’s home getting treatment for mental and physical recovery.. The whole property my father in law got from his forefathers. Only he build home. Please let me know that what kind of right my mother in-law ( second wife) has on existing property including home property and how she get it from the court and whom she need to communicate for this issue . Please help her with your value be advice... Thanks in advance... Ramireddy