recovery suit after 13 year is possible ?

Hello, I want to buy the land in native town. I have registered sale deed agreement between me (“A”) and seller (“B”). but still not yet registered the land. But 2002 seller (“B”) bought this property from Seller(“C”) , That seller (“C”) has four son ,One of the son given recovery notice to me and Seller (“B”). The problem is, He was arguing “I didn’t sign the sale deed in 2002 and that is not mine that sign”. But the document has his signature and thumb press. Even though he is arguing like signature not mine But seller (“B”) trying to register the land to my name and collect money from me. (1) Is it correct for registering the property to my name? (2) Running court case will it impact me if I registered this property? (3) Seller (B) saying he will face all court problem against seller (“C”) Son. Is it true/ or possible? (4) Or shall I make registration the land ¾ parts? Or register full with keeping some balance amount for ¼ properties? Thanks Arul