Backup external database

Using the B&R module, is it possible to get an external database backed up as part of the main backup tarball? After a quick look at the module, I’m looking at running a post-backup script that: 1)checks the backup directory for the most recent file, 2)unpacks it, 3)adds the output from mysqldump, and then 4)packs it back up again. There must be a better way to save my a2billing config as part of the backup.