NEED EMERGENCY ASSISTANCE

Q: My parents have purchased a land in Bangalore during 1992 under GPA registration. We did not registered the same. The land purchase as follow A party has been registered to B party. B party has given GPA to C party. C party has sold the land from GPA to us. Now I am planning to sell the land but the customer are telling that the documents has not been registered. During that time they have paid Betterment charges, Khata and paid up to date taxes etc., Now it has come under BBMP Limits. I have already taken A Khata, Khata Extract & EC from BBMP. Everyone are telling to find B party who has given GPA to C party (C party is not alive). We could not find B party. The stamp vendors agents are telling if you want to sell the land, first you transfer the document from your mother under gift deed and get is registered and later you can sell the land without any problem. Please let me know if i can proceed and doesnot get any problem in future. Once the gift deed procedure is over all the docuements like Khata, EC, Taxes every thing will be under any one of the family member name. Is it true, please explain and help me how to proceed further

Now one of the person is intersted to take the land and he is telling to provide the family tree certificate. After selling this land to the party by registering the document which i think Khata and extract will be tranferred. After doing this i will get any problem in future. Please inform immediately