Treaty does not have purchaser''s name is it valid

Borrower firm declared NPA and guarantors property was already published in newspaper by bank for recovery notice 60 days after we would auction property,now borrower firm with mutual acceptance with bank came to a amount to settle due with rs 60 for total of rs 100, now can bank settle amount of rs 60 Under one time settlement for rs 10 and another amount of rs 50 by private treaty combining both the modes together.now the owner on paper signed only one document with borrower saying executing private treaty amount rs 50without naming a word for purchaser's identity.now private treaty sale with purchaser was done by borrower firm not the owner. Can the private treaty declare null & void