I appreciate your time to write us regarding this preference. I can share some insights about adding multiple customer credit cards in QBO.
At the moment, you can only add one credit card information per customer profile in QuickBooks. Having this option is great idea we can add to our program.
While this option is not yet available, I'd recommend sending a product request to our developers. Doing this will let them know what features would help a business like yours run even better, and they will consider that in a future update.