If a customer pays cash for a Cashier's Check...do we include the bank's account number for the Cashiers Check account as the account number affected and check Box 31 "Negotiable Instruments purchased" or just check Box 31 and leave "account numbers affected" blank?

I know I have seen this somewhere and I can't find the answer. Thanks in advance for answering this very basic question.

Yes, if your Cashier's Checks are drawn off your bank, then list the account number under Box 35. If your Cashier's Checks are not drawn off your bank, then leave it blank.

Thank you so much! I knew that in my "heart of hearts" but I couldn't find something to back me up.