Hello, @KevinDiehl.

The option to edit the template when choosing to combine multiple invoices in one email is still unavailable. That would be a great addition to our current features, so I'll keep that on a note. For additional details on how to provide feedback to enhance the program, see this article: How do I submit feedback?.

You can also see other suggestions and vote for this product feedback by going to this link: Customer Feedback for QuickBooks Online. 

We make sure to take notes and address all feedback for QuickBooks Online as possible as we can. You can always visit the QuickBooks Blog site to check the latest feature added to the application.

Please feel free to visit us here on the Community page if you have any other invoice concerns, I'll be always here to help you. Have a great day ahead!