Is mutation of land necessary for land

My father had purchased a land of 3 katas out of 6 katas from my Uncle and done regisyration of the land. Now my father and uncle both are nomore and some other person taken the possession of my uncles land by giving some money to my aunty. Now the person is trying to sell the land and I fear that the person might include my land also for selling as my father had not done any mutation of the land. Please suggest me what I should do now by understsnding the above said situation. Thanking you.