Legal heir won the partition suit and original buyer put cheating case

Sir ,my late maternal grandfather died in 1996.he has land of 4.69 acres.he has 2 heirs .my mother and uncle.my uncle sons put partition suit in 98.in 2006 my mother and my uncle sold land to 3rd party for 2,65,000 informing that civil suit pending.in 2010,my uncle sons got exparte decree and got two shares of land.then third party put criminal case in court for cheating.now market value is over 20 lakhs.how to solve.