Thanks for reaching out, @Kelly2. I'll provide clarifications to your query about adding credit card to your QuickBooks Bill Pay.
As of the moment, the credit card option is unavailable in QuickBooks Bill Pay. You can visit this link for more information: How does online QuickBooks Bill Pay work?
Furthermore, you can schedule payments for a hassle-free process and improve cash flow management using QuickBooks Online (QBO).
Please let us know if you have further questions about QuickBooks Bill Pay. We're here to respond as soon as we can. Have a good one.