Ex-parte on property after 10 years how to cancel pending suit

My uncle sons put case for partition suit on paternal grandfather house and land in 1998. My maternal grandfather died in 1996. He does not have any will.it is self acquired. Now in 2006, when the partition suit pending . my mother and my uncle sold land to third party informing civil suit pending.they agreed .then sold for 2,65,000 rupees.the third party sold land to fourth party in 2009. But in main case, exparte decree got by uncle sons in 2010. Uncle sons threatened 4 th party and he returned land to 3rd party. Now 3rd party filed criminal case in court under sec 420 cheating case against by my uncle and mother. Now the market value is 25 lakhs. Now how to cancel the sale deed registered in 2006.for how much rs? Who to file ? By my uncle and mother together? What is the procedure? Clearly explain.how to relieve from this ? If put case to cancel deed ? What will happen? How much did judge order to give? Kindly explain.mother filed set aside petition in 2014. It is pending. What should we do?