Cost of Sales or Purchases?

I was bugged by this problem since my tax partner assigned me to fill the corporate tax return (Form C) for our clients.

1. The other tax partner, her husband is of the view that if there is no purchases in the statement of accounts, but there is gross profit stated in the accounts, the cost of sales figure should be stated as he said it looks wierd to have gross profit when there is no
2. My senior executive colleague, I is of the view that cost of sales is equal to purchases. ( this is something that I do not agree as by accounting definition, cost of sales is made up of opening stock, purchases and closing stock)
3. My supervisor A, fellow colleague, WH and I are of the view that purchases should be input only if the statement of accounts states that there is purchases in the account.

I am in a state of confusion now on how to solve this problem. As WH puts it, it will be hard to work as a team if this small thing blows up.

Should I send an e-mail to IRAS to seek clarification? The question is would IRAS reply over such a small issue? There has been instances that I have sought clarification from them but no answer was received.

I wonder what is a good way to solve the problem? Should I bring it up at a dept meeting?