Property Redevelopment & Selling the flat.

My mother resides in Mumbai in 350sqft flat. In our flat agreement there are 3 names 1. Grandmother (Demised) 2. My Mother 3. My Maternal Uncle. As per our grandmother's WILL, my mother will stay in this flat till she is alive even if the flat goes for redevelopment. After my mother's demise the flat should be sold out and the amount should be divided between the children of all her daughters. (My grandmother have 6 daughter including my mother). Now, due to bad condition of the building, the members of the society has decided to sell the whole building to a particular builder. (In which the builder will pay the market value of the flat). P.S: My mother resides in this flat since 22 years and also pays the maintenance and other expenses of the building. One out of 6 daughters is expired and she has 2 sons. My Questions: 1. In this case, it is considered as a part of Redevelopment or Selling the flat? 2. Can my mother take the whole amount from the builder and purchase a new flat? 3. If not, can she sell her share of the flat? (Is other heirs NOC required in this case?) 4. Can she purchase new flat from the same amount and put the names of other heirs in her WILL? 5. Or please suggest any other options available.