Property Rights of great grand son

Dear Sir/ Madam, My great grand father has one daughter and 4 sons. My father is one of the son to my grand mother. she died 20 years ago. Till now ( from past 10 years) we are residenting in place which was given by my great grand father to my garnd mother orally. now suddenly one of my uncle ( grand son of my great grand father) quarrel with my father for vating the place immediatly. Now my father is planing to file a suit against him. Is my father get any rights on my great grand father's property?? My uncle said that my father wouldn't get any right on my great grand father's property as he is son of my grand mother(lady). Now we are in trouble because we dont have any documents .But we are in possession in same place about 10 years. In revenue fair adagals also 4 son's ( great grand father's sons ) names are available but my grand mother's name is not there. MY uncle had only Fair adagal (RSR) copy no registration document is available with him. 1.Pleas explain me the rights of a daughter on his father's property ?? 2. will my father get any right on my great grand father's property? ? 3.If we file a suit against my uncle will v get property rights? ? 4. is revenue fair adagal (RSR) copy will give full rights on property pls explain. Thanks sekar