Sister right on father's property after marriage

Dear sir/madam, My sister got married in 2018 at the time of marriage my brother in law and sister both are second marriage my sister taken legally divorce from first husband but my brother in law divorce was pending in court she knows it but never questioned now after 3 years of marriage they had a baby boy now she came to our house and she is questioning from our house and my brother in law came to our house she complained to police and 498a case was booked now she is questioning about first marriage of my brother in law legal divorce my brother in law told my first marriage came to end because my wife is having medical issues and born baby is having talsemenia disease so their parents told that we will take care of our baby and daughter so please give what ever financial issues so they solved it on village head people and they are having video proof but what happened my brother in law and first wife two times attended in court but after that due to medical and health issues she didn't attended the court on humanitarian grounds my brother in law didn't forced to call them to court so the first petition was dismissed now my sister and his boy are staying from past one year and now she is questioning and put 498a case my mother was completely supporting to my sister and they both staying in one of the bedroom in my house me my father and my wife are staying in other rooms they are cooking separately now my mom and sister threating us and she is scolding man handling to my father and to me to give share on property now my brother in law again filed a fresh petition for divorce with first wife it is in due process you know due to covid it was delay in the meanwhile my brother in law came to our house and their parents came to our house asked my sister to come but she is refused what I came to know both my mother and sister are planning to take divorce and share on my father property now tell me is there in legality on my sister demand