A few thoughts on the copy that's targeted for the hold - if the item is already on the Holds Shelf or In transit, retargeting can be problematic and leave copies stranded.
Another option could be to transfer the hold along with the copy. This wouldn't be appropriate in Bill's use case, but another use case could be that Bib B is a different edition of the same work that was originally ordered, and eligible to fill the original hold. It's not a one size fits all.
Maybe a warning to the user that the holds will be retargeted and an option to cancel the operation so the holds could be dealt with manually before the lineitem is moved?
A few thoughts on the copy that's targeted for the hold - if the item is already on the Holds Shelf or In transit, retargeting can be problematic and leave copies stranded.
Another option could be to transfer the hold along with the copy. This wouldn't be appropriate in Bill's use case, but another use case could be that Bib B is a different edition of the same work that was originally ordered, and eligible to fill the original hold. It's not a one size fits all.
Maybe a warning to the user that the holds will be retargeted and an option to cancel the operation so the holds could be dealt with manually before the lineitem is moved?