If the voice mail is transferring to the Operator station then its a single transfered call. You can call forward the Operators phone to another, unless that phone has voice mail.
You should have the transfer out of VM goto a Phantom and ring, delay ring multiple stations.This change would have to be made on the telephone programming side and the Stratagy voice mail programming side.
If your not trained on the programming of these two systems then I would advise not to attempt it but get a certified technician to get it accomplished in the quickest most painless fashion.