After family agreement about property uncle filed case to get property

In existence of grandpa, my uncle made property allotment deed fraudulently on rs.5 stamp paper in 1984 by which he get this land no 194 in his name This matter came in to the picture when actual property allotment arise in 1997 in the family in the existence of my grandpa. And in family decision land no 194 which took by my uncle in 1984 allotted to my dad through an acceptance letter in presence of village talati, which entry approved by Nayab Mamlatdar in 1997. After 1997 till now my dad is the owner of the land and hold possession without any dispute and farming every year. Now issue arise here in 2012, RTS Appeal, and claimed (After 15 years) he is the real owner of the land In which judgement came in our favour. Now my question Can his appeal case be valid (Sustain) even after 15yrs ? Can he able to go further ? He also threaten us, if we win again, he will file civil suit against my dad, so what precaution we need to take ? Really appreciated your time and effort. Thanks a lot