Notarized spa

Sir/Mam, My father got paralyzed in 2018 due to which he was bed ridden. There is a property in Delhi which was allotted to our grand father in 1950. He expired in 1976 and post that no property documentation was done. In 2020 we all agreed including my Paternal Aunt's to do a relinquishment deed in favor of my father. Which was duly done and locked at registrar's/magistrate office. However, since he was ill to avoid any administrative hassles as my father was ill we thought of making a gift deed in my name. But as we was not well we got a SPA done in name of my Mother which was duly notarized and witnessed by my only Didi and Jeejaji. Basis that SPA my Mother executed gift deed in my name. Same was duly registered and locked at registrar's office. DORIS portal also shows document in my name via git deed from SPA of my father. I have paid 1.2 lakhs as tax to government as well. We were selling the house couple of days back but the person said our papers are not right as SPA is not registered and even registered Gift deed has no value. Can you please suggest. Regards Himanshu Kohli