To summarize: You want the Order Confirmation to go to the buyer, not accounting or the receiver (ship to). I'll assume there are multiple buyers for a single customer.
I can't think of any way to go this within the existing structure of Adagio, while still maintinaing the other email address fields as you have indicated. We have done a lot of things with PrintBoss, including conditional emailing. If you would like to contact us offline we could discuss your requirements further and see what kind of solution is possible.