Property partition between christian sisters and brothers

My grandfather (mother's father) had died without leaving a will in 1983. The land is divided into a family bungalow (where my uncle and his family live) and a smaller bungalow that was leased out to my mother in 1975 to build her own bungalow on. Her other sister is also a leasee being given a room in the family bungalow to live with her husband for a few years. On the day of their respective marriages, my mother and my father and her younger sister and her husband were made to sign agreements to accept cash of Rs 5000 and jewellery (basically their wedding jewellery) and not claim ownership