Clarification regarding drafting will or gifting ancestral property

Unmovable property purchased by my Great-grand-father, after partition among 3 Grand-fathers through Court, my Grand-father got a part of land and a part of house. He has two sons and a married daughter. After expire of my mother (left 2 sons) and aunt (left one son and 3 daughter) my father and uncle remarried. By second wife my father has a son and a daughter and uncle has a daughter only. My father and uncle built their own home and living apart from us. After re-marriage of my father they forget me and after 15 years they forget my elder brother too. we are living with my Grand-father. I am employed but my brother is not. My Father and uncle has filed a TPS against My Grandfather, myself and my brother for 1/3 partition of property among for Grand-father, Father and Uncle . My Grand-father was suffering from Lung Cancer, he gifted 1/3rd to me and my brother again he made a registered will for some more properties and passed away. pls tell me the legal aspects with reference.