What would you do if you were me (I mean, besides suicide or extensive
plastic surgery)?

Our original plan was to backup the data groups in each production
account before and after nightly processing. After processing, we would
then stream a differential backup (since the weekly full backup),
excluding those data groups in production accounts that we had just
backed up. We wanted this to be unattended, with third-party software
paging the on-site ops if any part of this flushed its job. So we wanted
to use auto-reply, and just have ops to swap tapes each morning. We
would like to keep this as close to free from human intervention as
possible. But the absence of an append option for TurboSTORE seems to
preclude that.

We are considering all options: third-party backup software that allows
appending to tape, or changing this backup procedure to allow as much
recovery as possible but just backing up once, or coming up with some
really great hack to allow us to append to tapes, or just insisting that
ops keep inserting tapes throughout the night. Considered opinions
welcome.