Pagdi System House Transfer Rule
So I live in a house in Mumbai that was purchased/leased by my great grandfather several decades back! My grandfather was born in this house with another four siblings and then my dad and many of his cousins were born here and then I and my siblings with several other cousins were born here too. During this time apparently the buildings landlord has changed which was only a few years back. We don't know if that is practically possible because apparently the building is in the name of a trust and not a single individual and hence we've been told it can't be sold by an individual to another individual. The problem now is since the new "landlord" has become the "landlord" she hasn't collected rent. Not once. Now out of all families it's just my family who stays in this house and everyone else has moved out having bought new homes.
We want to now sell off this house but most probably there wasn't any transfer of names since the time of my grandfather which can cause problems it seems. The new landlord has challenged us that she can get us kicked out of the house since we've been residing here "illegally". From electricity to gas bills and all our documents(passport, license, pan card etc) everything is registered on this address can that help.
I need to know what measures/documents we will need to take once we decide to sell and may face problems from the landlords end.
Any kind of help would be greatly appreciated.