[Michael_G]

110 songs referencing 11 files.
I assume your 10 original songs use 10 different PDFs. The newly added 100 songs all refer to the same single PDF file.

The "Files" tab of the song editor shows what's happening. Just look at the fields "Files:" and "Page Order:"

So if I understand this correctly, the CSV populates song data fields and aids in the import however, the songs will be imported individually and appear in the Songs tab as individual entries which in my case means I may end up with 10 versions of the same song unless I deselect the ones I don't want...?
 

Hi Scherzo,

perhaps a combination of importing Fake Books via csv-File and using "Collections" lead to the goal.

Put all your "real" songs in one "main" collection and create a new collections for each via csv imported fake book. 
Do not use the song tab in the library but the collections tab, choose your main collection and start from this point (it is possible to configure mobilesheets starting with the collections tab choosed). 
So not "Songs" is the real starting point for you but your main collection. Forget the songs-tab ;-) 
(Thats my handling, i have sheets for the whole sax section and switch between the sheets for the needed instrument via collections during one single gig.)

If you need a song from a fake book, change to the corresponding collection.

For editing setlists you can use filtering to show only songs from a desired collections. 

Maybe this is helpful.

Cheers Michael