Necessity for release deed

My father has a house in Tamil Nadu, originally in my grandmother's name. After my grandparents expired (without any will), my father paid his only sister's share recently and got the property transferred in his name. Now, my father with 2 sons & 1 daughter, wants to release my sister (married) from the property to ensure that it belongs to my father and then my mother till their life time and then finally it will be divided between his two sons. Considering this, what's the best option available for my father : (1) execute only a settlement deed with my sister as witness or (2) execute release deed for my sister & then go for settlement deed. Kindly advice.