Thanks for your suggestions.  You've understood what we need.  For now we're trying Zapier.  My idea may have been over-simplifying things - a button to take you to the payment option in Stripe, like you can to pay in PayPal.  However, I can create a payment code in Stripe and copy that to the Client's invoice in QuickBooks - but my thoughts are "why bother?" so I'm setting clients up in Stripe and moving away from QuickBooks, as the French version has so many bugs, the dashboard does not show the information we need, and the customer support is painful to say the least.  If we had in-house coders that would help, but we are a small business so the staff multi-task.  Thank you again for your support.