Property Transfer

My mother bought a house in 2003 and it had 3 floors and we got that registered to our mother name. Out of those 3 floors I paid for 1 floor to my mother and younger brother with which she is currently staying. I got 1 more extra floor because I signed the NOC and Relinquishment deed that in my ancestral property I do not have any right and my brother and mother gave me that extra floor in new house as a replacement of my share in original ancestral property. Now I have 2 floor and younger brother has 1. Later my younger brother acted as builder and re-construct the house and got one more floor.Now we want to transfer those 4 floors with2 floor in my name and 2 floor in younger brother name. For this we have we have mutual agreement, but in doing this we do not want to include our sister as she might object. Please advise the best way to get this transferred to our name so that no one can challenge it in future, whether it is my sister, younger brother or there heirs.Please note that property is freehold and in name of my mother with my younger brother has its power of Attorney rights.