Query regarding indemnity bond and transfer charges related to a pagdi shop

We were not paying rent to the landlord to his demand as he was charging 3X rent, we tried to pay by cash, but he returned it. We paid by pay order and he returned that amount, we had done this multiple times so that we could be safe on our side if he approaches court. As per the letter/notice we have cleared all the rent dues as the family dint wanted to go for any legal battle. We paid the rent and replied to the letter defending our situation. Now I would like to ask few imp things, the original rent agreement for this pagdi shop was on my grandfather’s name (deceased now). Till date we never gave any death certificate or any official letter for changing of name to any of my grandfather’s legal representative or legal heirs (grandfathers children). Now the landlord has requested us to furnish the details of legal heirs so that rent receipts could be transferred to the tenant’s name. the landlord wants this to be executed and declared on the indemnity bond. How is this done? And after this step how much transfer fees the landlord can demand legally to transfer the agreement to the legal heirs’ name? The landlord argues that in the rent agreement of my grandfather, it was agreed to do only one business and now as well no other business can be done at this unit. Suppose a new amended agreement is made and the landlord directs that only previous business should be continued or face legal actions than how this situation can be dealt? Is the previous agreement gets nullified in such a situation? Can we do other legal business, or it would be difficult to change the initial business. By not letting to do any change of business is it harassment from the landlord?