Rules for Redevelopment of Paghadi System Building, Mumbai

Dear Sir, I am a tenant of a Building in Kandivali West, Mumbai. (Pagadi System), The building is more than 40 years old. The area of everybody's home is different (single room 140 / 155 / 170/ 185 and double room 310 / 330 sq. Feet). Now, landlord & tenants are appointing a builder for redevelopment. Builder was asked, he redevelop 250 sq. feet & 400 sq. feet, and we will get only 7% more of our space, and other difference square feet we have to pay him and he will pay rent only Rs.50/- per sq. feet. The property is registered on my Father's name, who is a senior citizen. Thus, I want to know as per law, what area (sq. feet) we get after redevelopment, and how much we get rent from beginning to end to stay and brokerage and loading - unloading (transportation) too. And what the benefits we can get? you are requested to reply with all other details, which is very helpful to me. I am unable to write properly, hope fully to understand my points. Thanks & Best Regards Ashwin D.