Salaami Shop Subletting or Selling Off

Hello Sir , My father and grandfather had took three shops on salaami from our landlord around 30 years ago. Now my father has happened to expire the previous year , while my grandfather is still alive. The rent receipt as till my fathers death was on the name of my father and grandfather. The property was actually under my fathers control. My grand father is still alive and is ready to sign on the NOC for the shop. Also , the legal heir of my father is my mother and we two brothers. Presently the rent is 1056 per month and increases by 10% every three years as per the landlord. Out of the three shops one of the shops was rented to another tenant in the same building few years back under mutual agreement with my father. The landlord had then created issues regarding the matter. According to him we cannot put the shops on further rent. Hence the third shop which was on rental agreement , was under mutual understanding with my father , the buyer and the Landlord was transferred to them against money , a part of which was paid to the landlord. Now the remaining two shops are used by me and my brother for commercial purpose as our office. Owing to weak financial position and problems of having shop on the 2nd Floor , we wanted to shift to ground floor. Now on putting up a FOR SALE / FOR RENT notice on our shop , the Landlord has objected on us for doing so and asked us to remove the notice as it is illegal. Please guide me the process to sell or put the shop on rent so i could afford another commercial space in the ground floor. P.S. 1. My father is dead and we are the legal heirs, also my grandfather is ready to sign the NOC , so how to transfer the rent receipt on our names? 2. As per my research online , we can legally stay here up to 5 years from the date of death of the tenant. After five years can he push us out from here ? 3. If we wish to rent out or sell the property what would be the legal process to do so ? 4. The landlord is taking the rent but not giving a receipt since he says issuing a receipt on the name of dead person is not legal. So what should we do now ? Note : 1. We do not have the agreement papers as between my father and the landlord 2. The only proof we have is the old rent receipts on the name of my father and grandfather