• Ancestral property in grandfather's name

My grand father’s father was partitioned his self acquired properties in 1965 with his sons. In that partition deed my grand father got a house and some lands. Lands are sold away before 1985. My grand father has 2 sons and 2 daughters. All are married before 1983.

My father is second son to my grand father, From 1985 to 2000 my father only maintained our grand father and grand mother. in 2000 My father expired. 
my grand father (age 80) wrote a settlement deed in favour of his one deased son’s  two children (age 25 & 30)  to maintain himself and his wife in 2002.  

In 2010 my grand father died. 
In 2011 my grand father’s another son and 2 daughters filled a suit to divide the property. And my 2 aunties take my grand mother with them to get her share for them.
They are asking equal share in the property (house)

My grand father’s settlement deed is registered in 2002. is it Valid?