Capital gains

The partner has sold an alto car worth Rs.2,00,000/- and purchased Swift Dzire Car. The old car amount is set off against the new car purchase value. But the Car is recognized in the firms name and the Asset as well as the loan attached to it is disclosed in the firm name? The returns of the firm is already filed for the Ay 2016-17 What can be done and how the entries to be passed in the books of the Partner? Please answer as soon as possible