VS Mail limits your options.
If you set the Transfer Return Extension (#306) for each voice mail port to go to themselves instead of Ext. 10, a transfer to a calling group will ring, then return to the VS Mail, which won't know what to do with the call, and announce "Transferring to Receptionist", send the call to Ext. 10, which will then ring and if still unanswered, cover to Mailbox 10.
You could also loop an extension to a CO port, add the extension to the calling group, add the "CO" to a phone and have that phone cover the "line"