Reg Land sold and still occupied by seller

Hi, Thanks in advance for the help. 3 years back I had bought a piece of land from a family friend. This Piece of land is 11 cents and the owner has about 60 cents of land. Since the seller was very close to my father, my father didnt bother much on the legal side. Based on the trust we had on him, my father bought the land. Now, there isnt any legal issues with the land. But, the Piece of land which we bought, doesnt have a drawing in the sale deed. This sale deed was prepared by the seller only through his lawyer. Now, since the drawing isnt very clear, and since this is not a layout(just a part of land from a big land), the revenue officials are not giving the subdivision patta in my name. Also, the land owner after selling pieces of land, has started a business in his land and is not willing to give our part of land. After few years, the land is also not identifiable. This is the issue now. When asked for our part of land, he is simply saying to our occupy the land after getting patta, whereas the Revenue officials are saying that they will not be able to issue Patta since the land is not clearly demarked in records. Please advise how to resolve this issue.