Print & Delivery Group emails

I worked with my partner who entered a ticket with Boyum for which there is no resolution.  My scenario is this...

We have many Report Configurations, report actions, mass delivery configurations, and schedules set up to automatically email various documents to internal and external recipients.  For those that have a single report in the report configuration, the group emails by document feature generates a single email with all of the To, CC, and BCC recipients.  On one of our report configurations, we include both the sales order and the delivery in a single email.  The expected behavior is that a single email would be generated with both attachments.  Instead, a separate email is generated for each recipients (even two email addresses in the "To" field in the report action generates two emails.  Each email is identical in every respect except for the recipient.  Boyum's response is that group email by document is not supported in this scenario, but one would think if the documents are the same between recipients, it should be grouped as expected.

I'm aware of a workaround of saving the documents somewhere first, then retrieving them to send them out.  We do not want to go down that route.  We are high volume and are already being pressed about drive space in our cloud environment.