Sale deed not registered on 1998-Chennai

My father bought a house from a person in chennai on 1993 and settled to my brother (polio affected 80% disability could't walk) and a house sale deed executed in register office for house only (not for land). Since the land belong to Tamilnadu slum clearance board the land was allocated to the seller (the person with whom we bought the house) on 1998 and a sale deed was given to him by slum clearance board after paying the required amount to the gov't but that sale deed has not been registered in register office on 1998 can we register that same sale deed now (execution date was not mentioned in that sale deed) after paying the required fine or should we again approach to slum clearance board for getting new sale deed. The seller have already given his consent in writing (but not registered) that he will transfer the title of the land too once if he gets allotment from slum clearance board. Kindly note from 1993 we are paying all taxes including property and water tax in my brother's name.