Lease Given on Agriculture Land

I am from Karnataka My Grandfathers who have given our Agriculture land to Lease to a Person called Krishnappa in the year 1982-83 and a Mutation Record is showed as Lease to Krishnappa with MR [deleted] in the RTC We don't have the Lease agreement copy with us and we got to know that Lessee Krishnappa is no longer alive We tried to get the Certified Copy from Sub Registrar Office, but the copy is not Clear to read the agreement, Mutation Record collected from Tahsildar office is also not clear how much amount was collected for lease and what was the terms of Lease. We are ready to pay back the Lease amount with Interest to the Krishnappa and Family Land is in our possession only, when we try to sell this land, the buyer is asking us to get this Mutation Record removed from RTC Lessee Krishnappa's Grandsons are asking for Lakhs of Rupees to support in removing this MR from RTC What is the legal procedure to remove this Lease MR from agriculture land RTC? Does Lessee or his family members have Right in this Land? is it True that if the Lease MR is not removed from RTC in specified time that Lessee or his family has the Owner ship of the land?