Property law

My father was adopted in 3 months baby and his adopted father and mother didn't make any legal records on it, after few year the first wife of adopted mother paased away with some health issue and after few years, the adopted father took some property in that he wrote his adopted son as foster son in Karnataka everyone has ascent of saying saku maga means foster son not dattu putra. He(adopted father )was saying i took care him. Later he married another lady he got 3 childrens and at now he made a gift deed of property to his second wife and that second wife is saying he (adopted father )mentioned as foster son and you do not have any right and she forcing us to vacate and at current adopted father also no more. We are locked in such situation were how to claim, in all documents and records adopted father mentioned as his son. Can my father has any rights....