How can I get Outlook 2011 for Mac to save SENT messages from a shared mailbox to the Sent folder instead of the Drafts folder? 

Details:  Our Support department has reps that are using Mac's (Office 2011 for Mac) and Windows (Office 2010 Pro) and have a Support shared mailbox that they have added to their Outlook clients for easy access. The following problem is on the Mac side only.  When the shared mailbox account is added to Outlook 2011 and they send an email 'From' that mailbox, the email is first sent to the Outbox and then it is successfully sent out, but it is then saved in the rep's personal 'Drafts' folder instead of the Sent folder for that shared mailbox.  The support reps have 'full access' and 'send as' permissions from the shared mailbox.  There are not any server rules in place for outgoing emails for that shared mailbox.  The Windows Outlook client does not have this issue and saves the email to the Sent folder.
I gave myself permissions to this shared mailbox to test and troubleshoot and here is what I have done (from a Mac with Office 2011):
-Added the shared mailbox using 'File - Open - Other User's Folder' - this only adds the Inbox and emails sent From the shared mailbox this way are saved in MY Sent folder (makes sense because the shared mailbox's Sent folder isn't accessible this way).  However the reps need to also view the messages Sent from the shared mailbox so this is not an acceptable workaround.
-Created an outgoing rule in the Outlook 2011 client to copy messages to that shared mailbox's Sent folder.  The rule didn't work and so behavior did not change.
-Created a new shared mailbox (as a test).  Same behavior happens.
-Installed software updates and Outlook is version 14.1.0. Same behavior.

The reps are able to access the shared mailbox via their 365 Outlook access.  However they would prefer to work in this shared mailbox via their Outlook client.

Thank you, in advance, for any guidance you can offer.

Janet