Voice Mail messages

I have a client that has a regular extension on her phone and a DID that goes to another extension on her phone. She receives V/M on the private line and would like to only have to check one mailbox for messages. is it possible to answer the private line with the Private line message, record the V/M and then send the V/M to the Mailbox of the other extension. It can either be copied to transferred. Transferred would be the best solution. Any suggestions?

Thanks in advance for all of your help!

Yes, it is completely possible. A ring group would make it easy. There are three greeting associated with each mailbox.