OC is not a vital document to sell the property neither the SRO will insist on OC to register the sale deed in favor of the purchaser.
Since the property has been purchased 10 years there is no necessity to obtain OC at this stage.
Actually an OC certifies that the construction of the building has complied with the approved plans. It is issued by local municipal authorities or the building proposal department once the building has been completed and is ready to be occupied.
Therefore this OC do not play any role to the title of the property.
The Occupancy Certificate (OC) is a document issued by a statutory authority (such as BBMP and BDA in Bangalore) and it gives the applicant (builder) permission to “occupy” the property. It is required for commercial buildings and for residential buildings that have more than five units.
Therefore if your apartment complex is more than five units then the builder would have obtained the OC without which the services namely electricity, water supply would not have been provided by authorities concerned.
In any case you can approach the legal heirs of the seller to provide you the desired OC if it was not given to you then, after which you can plan to approach the BBMP authorities concerned.