How my father can get his property partitioned?

How my father can get his property partitioned? My grandfather had 2 sons and 1 daughter. He built a first floored house and later my father and my uncle started living there. Due to some tension among them, they constructed a wall between the house and both my father and my uncle constructed 1st floor of their respective house (divided by the partition wall). My grandfather died on 2003 without any will. Grandmother is also dead. My paternal aunty got married on 1981 and lived in a separate place with her husband. Now my father want to get his portion of the property. I heard about some amendment of property law on 2005 and later some new amendment on 2nd Nov 2015. My questions are as below. 1. Do my paternal aunty will also get 1/3rd of the property (my grandfather died on 2003)? 2. Is it possible for my father to sell his portion of the property to someone else without consent of my uncle and paternal aunty? 3. Is it possible for my father to authorize someone else his share on the property on bahalf of money? 4. My father is staying in the property since 1987. what are the possibilities that he can sell his property to someone else? 5.Is it possible for my father to lease his portion of the house (ground floor constructed by grandfather and 1st floor by my father) to someone else for 99 years? Any valuable suggestions are welcome. Thanks and Regards, Raj