What are the complications in transfer of property

one of my known person recently sold a property which was disputed for last 15 yrs. they had given the kabza to the initial buyer 15yrs ago, but the buyer did not take the house instead asked them to stay at the same place. 15yrs passed and he was not willing to give the amount for the sale. now my collegue has sold the property to someone at a much lower price. what are the complicATIONS IN THIS CASE