What really complicates this is your recovery plan. Are you going from a
multiple drive library to a single drive library at your backup site? I
know, you aren't planning on recovering at your backup site unless you
take a missile hit during the upgrade.
If all your concerned about is a multiple drive restore using the same
hardware I would think that BRMS should have this all figured out.
IDK how big of a library you'd have to save to try a RSTLIBBRM (to a
different library) and get it to activate multiple drives.