[Zubersoft]

The song versioning feature (which will be added early next year most likely) may be the only way to solve this unless you want to set up separate libraries per band, as the song versioning would allow you to create multiple versions of the song with different metadata and pick which version to use for each setlist. If you don't want to rely on the numbering that MobileSheets uses (which is just the index) and instead want to have your own custom number at the start, you need to utilize song title formatting to put a different field at the start such as the custom field. 

Mike