Procedure of partition of property

Father expired in 2007, before  that he made gift deed for a property which v r living from past 40+ years on his 3 sons plus himself to reconstruct the old house by his 3 sons floor wise. Registration for this done for one son for ist floor & by god's grace eldest son constructed his share. Similarly after dad expiry 2nd son too done with his share of floor. As v got permission for only Ground + 2 stopped further. My query is b'coz of permission 3rd son says he was not given proper share in property. What is the solution. How can it b divided. 2. This was divided into 4 equal sq.yards by dad. One share on his name. Three for his sons. Now how to share this means Dad's share. We have a sister also. Does my father share to b divided again into 4. My query what does law says. Do v need to give our dads share or 1/4th of dad share., bcoz whatever presently constructed is of our money. Only land was divided into 4.