What is sister's claim on grandfathers property?

My Grandfather passed in 1997. Grandfather have one son and one Daughter, After Grandfather death my father's sister did relinquishment deed in fever of my father. My Father have 3 daughter and 1 son(my self) my father want to give his all property i.e 2/3 to his son(me). 1/3 of property is on my Grandmothers name,grandmother also want give his property to his grandson(me).(my fathers sister,her sons,my mother,and 2 sister also no objection on that) but one of my sister who is married want his share.and no one want to give property to her. my father want to do relinquishment deed in fever of my grandmother name.and then grandmother want to do will deed in fever of grandson name with witness of (my father,my Father sister/her son) 1. can we do that? 2. after my father relinquishment deed can she claim her share/relinquishment deed can challenged? 3. after my grandmother will deed can she claim on her share/will deed can challenged ?