Pagdi System

My family has a house in mumbai. The house comes under pagdi system. The house is in the name of grandmother. My grandmother died on 20 sept 16. The landlord lives in same locality of our house. My grandmother had 3 children- my dad the eldest, my uncle the middle one & youngest my aunt. The land lord is giving money to my dad, uncle & aunt for collecting No Objection Certificate so that he can sell the room to another party. Now all the rent reciepts of the family are in my grandmothers name. Now the landlord is paying 5 lakhs to my uncle, 3 lakhs to aunty & 2.5 lakhs to dad for NOC. My dad is demanding 5 lakhs, but the landlord refuses to pay 5 lakhs to us. We haven't paid the rent for 10 years of room. The landlord says he has the legal right to take possession of the room since we haven't paid the rent for 10 years. The landlord is forcing us to take 2.5 lakhs & give NOC. He is in very hurry to sell the room. 1. Please advice us that can landlord take the legal possession of the room, since we haven't paid rent for 10 years?. If so, 2. why is landlord forcing us to give NOC, what is the importance of NOC in this case. 3. What should we do in case?