Mortgage

In 2000 my mother bought property of 3 acres in pulivendula town from 2 brothers. At that time as she was unable to bear registration charges instead of registration she went for Mortgage registration and registered it on 12-June-2000 in Pulivendula sub registrar office.After 4 months(i.e on [deleted]) the persons who mortgaged the property made an agreement on Rs 50 stamp paper saying that we got money for this land and gave full rights to my mother and it was wriiten in the document we will come for registration in future at point of time if my mother asks for registration.In 2001 my mother got pattadar passbooks on her name.In pattadar passbook it was mentioned that my mother acquired propert by Mortgage(Kandimpu Ayakam).My father died in 2001 and my mother passed away in 2012. Now me and my brother are left with all the previous link documents,Mortgage registration document(Choopudu ayakam in telugu) and pattadar passbooks on my mother name with us.Is pattadar passbook, family certificate,death certificates of both my father and mother enough to apply for layout approval from Municipal corporation for the said land?Now as almost 16 years passed and since we are left with only Mortgage registered document do the previous owners have any chance to claim if we go for any developments in the said land?