Partition suit against the property of a man dying intestate

My maternal grandfather has house in tamilnadu and land in andhra.both are self acquired property. He was a retired doctor.he died intestate in 1996. He has two legal heirs one is my uncle and my mother. Uncle is alive.my uncles sons filed partition suit in Ongole court in 1998 requiring a share that my uncle is a drunken and he will sell the property.by that they got preliminary decree in 2005. Final decree got exparte in 2010. By that execution pending in local court vaniyambadi.now interim application filed in Ongole court to set aside exparte decree by my mother.now my doubt is whether paternal grandsons can claim a share in their grandfather property though my uncle is alive.one uncle son is 31 years old and second son is 22 years.another question is during trial, my uncle and mother sold 4.69 acres land to third party in 2006 informing that civil suit pending,they agreed.and gave 2,65,000 rupees.now my uncles sons threatened third party who filed sec 420 police case.how to solve