I have found the template files for Invoices located at: (VM v3)
components/com_virtuemart/views/invoice/tmpl/
But what is the the file associated with the notification sent to customers? I can't find the right file. (For example, I want to add a banner above the text, "Thank you for your order!" And I'd prefer to do this is PHP file directly)
Also, if anyone knows of any documentation for editing these files, please let me know.
Thank you!!
Jonathan