Is it OK to buy flat from 2nd ownr when saledeed betn 1st ownr and builder lost?

4 years ago

Is it safe to buy flat from 2nd owner when sale deed between 1st owner and builder is not available?
Process for acquiring duplicate Index II from office of registrars in name of 1st owner is in progress.

Available property docs

2nd owner deed of assignment/transfer
2nd owner Index II
Approved plan copy(xerox of blue print)
occupancy/completion certificate
commencement certificate
share certificate (indicates transfer to 2nd owner)
society maintenance receipt (in name of 2nd owner)
Latest electricity bill (in name of 2nd owner)
Latest property tax bill and receipt (in name of 2nd owner)
society registration certificate

Docs NOT available

Agreement for sale or sale deed between builder and 1st owner not available
Formal receipt of payment to builder by 1st owner not available.
Formal receipt of payment to 1st owner not available but mentioned in 2nd owner's deed of assignment.
Possession letter by builder to 1st owner not available.
Possession letter by 1st owner to 2nd owner not available.