I take it that the tenancy stood in the name of your GM
After her demise the tenancy would devolve on the family member who was living with the tenant at the time of her demise - see section 7(15)(d) of Maharashtra rent control act
That family member I assume was your late father and after him you are claiming the tenancy as his legal heir
So you become a statutory tenant under the above provision of the rent act
If you have paid the rent to the landlord and he is refusing to accept or having accepted the same , he has not issued the rent receipt, then you are not at fault
You still have the protection of the rent law
Also under the rent act not issuing the rent receipt is made an offence
You need not transfer any documents to your name. Whatever existing documents you have and the documents that stand in the name of the original tenant , would suffice
However as rightly apprehended by you the landlord may intentionally create complications by requiring you to get the noc of your aunt and uncle who are the other heirs of your GM who was the original tenant.
However if they are ok and consenting then you can always take their consent affidavit for record for submission to the landlord or any other authority
I don't know under which regulation of the DCPR 2034 the property can be taken up for redevelopment since its held by two entities, the land is owned by the landlord and the flats in the building are owned by the individual tenants (except you) who seem to have formed a society
However whenever such redevelopment takes place you will get the benefit of the redevelopment in the form of the new rehab premises in lieu of the old premises held by you at present
Just because you do not have ownership right over the flat and still hold tenancy rights, would not mean that you will be denied the redevelopment benefit
You should continue paying the rent to the landlord , even if he refuses and does not issue any receipt
You can write the amount and month on the covering letter that you would send to the landlord which will be an evidence that you regularly pay the rent. If you want to make payment by UPI ensure that the amount is credited to the correct account standing in the landlord's name. Otherwise you can continue issuing cheque or a DD (for consolidated rent of several months together , say for a year) which is also sufficient. Cheque has a validity period , however when you make a DD the amount would be debited right away to your account. So it's a good thing that you issue DD to the landlord towards rent.