So, here is what we're going to do.  We will not move the old backup
objects at all. The application admin will copy the current files
from the old clients to the new client, and revoke customer access to
the old clients. Then, we'll wait 'retonly' days (the longest time
any inactive file could be legitimately requested from the old
clients).  At that time, all inactive versions will have expired on
the old clients. Then, we'll delete the filespaces on the old clients.
QED

Keith Arbogast