[itsme]

"While MobileSheets supports "Collections", they are of almost no use if multiple "collections" of songs are VERY SIMILAR.g."
This is definitely wrong.

MobileSheets allows various solutions for your task. Here's one o them:
You could e.g. keep the same song titles and use a collection for each of your line-ups. With the collection / line-up in the database you need to make it visible on the songs tab and in the setlist editor. To do so add the collection via "Library Settings - Song Title Formatting" either to Title or Caption of the songs. Set "Show caption" and "Use formatted title for sorting".
So your different groups can easily share scores or have individual scores as required.
Filter by Collection while working with one of your groups and while preparing set lists.