In herited Property dispute

Hello, I seek guidance for my dad land no 194, which is inherited by my grandfather. Situation was little tricky so trying to elaborate in detail as follows. In existence of grandpa, my uncle made property allotment deed on rs.5 stamp paper in 1984 by which he get this land no 194 in his name and leave others survey no in grandpa's name, which is totally in absence of my dad, and he didn't sign it. 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. (Here acceptance letter is drafted in a paper in presence of Talati, which says "All brothers had discussed with their mutual understanding and alloting land, which will be acceptable to all of us" from which my dad gets land no. 194). 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, he applied under revenue law for a RTS Appeal, and claimed (After 15 years) he is the real owner of the land and my dad has took his land & so on... Which RTS Appeal came in the office for discussion in 2015 at Prant Adhikari, Kalol. in which judgement came in our favour. Because he applied after 15 years, which is long time duration with out valid reason. After that he appear for Collector office to appeal that judgement, which going to be discussed in next month Dec-2016. So, my question Is this his (my uncle) valid ground to fight for this land no. 194 ? Can his appeal case be valid (Sustain) even after 15yrs ? Can he able to go further ? If yes, how long he can go after Collector office, Gujarat ? He also threaten us, if we win again than he will file case under Civil matter, so land will not be saleable in future. What shall we took action in this matter. This is really painful to me, because my dad is farmer, and he is illiterate for this kind of matters, so i need to spend my time for this even in my exam days. And my uncle trying to get shortcut money through our land, because land rates are booming here. Can i request to guide me for my above queries. Thank you, and really appreciated your time!