There is sort of a way.....

If you read the installation manual for the VS mail, it tells you to set the Transfer Return Extension (#306) for each of the VM ports to Ext. 10 - so a call transferred from the VS to an extension without voicemail coverage will ring and then go to Ext. 10 if not answered. However, this does not work with groups, calls transferred from the VS to a calling group will ring forever and not return anywhere if unanswered.

Set #306 for each VS port to ITSELF - If (for instance) the VS ports are 31 and 32, set #306-31-31 and #306-32-32

Set the Transfer Return Rings in #105 to some reasonable number

Call transfers from VS to Calling Group Ext. 71. Rings the number of times specified in #105. No answer, and the call returns to the Voice Mail Port that did the original transfer. The VM port answers, but doesn't get any mode codes, doesn't know what to do, says "Transferring to Operator", and transfers to Ext. 10. Ext. 10 rings, isn't answered, and #321 for Ext. 10 controls how many more rings until Mailbox 10 answers.