Ancestor Property, How to transfer or registered on Grandchildren

We have a property in Delhi purchased by my Great Grandmother transferred to my Grandfather registered in the 60s, it was a Mortgage to some individual at that time. In the 80s, my father has freed the mortgage and along with proof submitted the relinquished deed to be the sole owner of that property. My father had lost the property paper with time but recently due to eabhilekh delhi govt website we have been able to find all the documents scan copy online which are in teeshazari it shows all the docs, sales deed, mortgage deed and relinquished deed but not the Stamp paper signed by the same Lender which said, the mortgage was freed although it was submitted along with the relinquished deed at that time. How do we get that property registered or transfer in my father or my name? We have found my Grandfather's documents, like his Death certificate of that address, the Army certificate of that address, rest property scan documents we have found on Govt website.