Thanks for following up on this thread, Robert804.
I'd like to provide some additional info about creating invoices for third parties in QuickBooks Online.
You're correct, the customer would need to manually modify the third party or alternate division mailing address for the invoice. There isn't currently a way for this info to be added to invoices automatically. I can see how having this option would be beneficial. In this instance, I recommend submitting feedback to the Product Development Team for review. This can be done directly through your QBO account by clicking the Gear icon in the top right corner then select Feedback.
After doing so keep an eye out on your emails and the Firm of the Future site as well for info about new feature releases and product updates that often come from great user suggestions like yours.
Please don't hesitate to reach back out if you have any other questions or concerns. I'll be here to help in any way that I can.