was it self acquired property of your great grand father ? did your great grand father leave any will or he died intestate ? how did your grand mother inherit the property? if your grand mother is absolute owner of property she can bequeath it by will or gift it to daughter . if it is ancestral property she cannot give whole [property to her daughter

How did the father of your grand mother receive this property? Did he purchase it solely from his own earning, or the other members of the family also contributed to the finances? If it can be proved that the father of your grand mother alone did not purchase the property then your father can legally question the right of his mother to give the entire property to her daughter.