I appreciate you for joining the thread, @JMG6.

I'll step forward to give some workaround for billing a sub-customer in QuickBooks Online.

With the help of this option, you can enter charges for a parent customer and a sub-customer to have both appear on the same invoice. Since you've mentioned that you don't want to bill your sub-customer, we can uncheck the Sub-customer checkbox. 

I'm also adding this article for additional insight into creating invoices.

In addition, if the customer pays the invoice, you'll have to record the payment. It is the best way to help your books balance. Check out this page as your reference: Record invoice payments in QuickBooks Online.

Don't hesitate to mention me if you need help with how to run your sales report in QuickBooks. I'd be happy to share some ideas with you.