Replacing tapes when tape loader has used all available tapes

Hi

I have a server with BE12 which backs up all my server on the network. Once a full backup is complete the job is then sent to the tape loader for duplication. The tape loader has the capacity for 24 tapes. my question is, when all the tapes have been used and a backup job is requesting to insert new media, how can i insert the new media and label it without having to cancel the job to run an inventory? i label my tapes as followes

1,2,3,4,5,6,7,8,9

1a,2a,3a,4a,5a,6a,

1b,2b,3b,4b,5b,6b

If i insert the scratch media as is, the job continues but labels the tape with a random name. now if i try to label the tape once the job is done it says it will clear the tape of all its contents.

whats the best practise for this?