Ancestral property's mutation not done since 1941

Dear Sir/ Madam, My great-grandfather's name along-with his 2 brother's names are currently appearing on the revenue records as three equal partners in my ancestral property. However, during 1941, via a registered award, those 2 of his brothers gave their share of this ancestral property to my great-grandfather, who then became the sole owner of this property. However, till this date, this Registered Award has not been implemented in the revenue records. Also, the original copy of the Registered Award is missing from our end and it is missing from the record room in the government office as well, which makes it even more difficult to get the intkaal done via such an old-missing document. After the death of my great grandfather, this property was passed down to my grandfather and now, it is with my father. So, we have had the possession of this property since the last 83 years and we still have the possession. Hence, what can be the best remedy for transferring this mutation in my father's name? Any suggestions would be really really helpful!