Pagadi property query in mumbai (hindu)

Hi, my mom ( Hindu) has been staying in the said tenanted house eversince she got married in 1957 and came to Mumbai.The said house (tenanted property (Pagadi System) in Mumbai) was purchased by my grandfather's younger brother (Mr A ).He passed away in 1964 and since then my father was paying the rent and after my father's demise my brother has been paying the rent but unfortunately we didn't change the name in the rent receipt and the receipts are still in my grandfather's younger brother's name ( i.e. Mr A ). We all brothers and sisters were born and brought up there.All our records like PAN card , Passport etc have its address. Now the said building is gone for redevelopment. The builder has entered into an agreement with all the other tenants and also paid them alternate accommodation amount but is not ready to enter into an agreement with us because now all of a sudden all the legal heirs of my younger grandfather ( Mr A ) want the agreement with the builder in their names and completely sideline my mother. I would like to know the following: Whether the legal heirs can go ahead legally and enter the agreement with the builder.(None of the legal heirs have been staying there since last 20-25 years.) It's my mother who has been staying there from 1957 till date. Can we legally enter into an agreement with the builder( though he is not ready to do it in the present situation). We have tried hard to settle the dispute within the family and have told them (legal heirs) that we are ready to share the amount but add our mother's name in the agreement but they are flatly refusing it. Under these circumstances what are the legal options available to us.How should we proceed further? Does any law in India protect my mother's rights ?