[Scherzo]

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...?
 
If that is the case, having more individual songs to scroll through when searching seals the deal for me. I don’t want to import all of the songs individually from the fake books and use the Songs list to find them. Regardless of the methodology used to import the songs from the fake books, (CSV or just extracting the individual songs as individual PDF's in Acrobat), adding even 25% what is represented in the 12 fake books I have as single-page PDF's will clutter my library with an additional 2000 songs that I will rarely, if ever use.
 
All I am after is a way to use the PDF master index I already have in my library that covers all 12 fake books. When I don't have a song as an individual file in my library, I want to be able look up a song in that master index then be able to enter the page number indicated into the requisite fake book and have the page number match the song I’m looking for, meaning ignore the fake book cover pages, indexes etc.
 
Interestingly enough from the enlightenment you provided, I discovered a simple suitable work around.
 
After I imported the 12 fake books & the master index into my MSP library, I modified each fake book title and added the page number range & the amount of pages I had to factor when trying to match the page number referenced in the master index to the page number in the actual PDF fake book.
 
For example, I renamed "The Real Book Vol I" to read The Real Book Vol I - Pages 1-512 [+13] with the 13 representing the value I have to add to the page number I enter so it ignores the cover pages & indexes and matches the page number referred to in the master index.
 
What I discovered after reading your post is I can manipulate which pages appear in what order in the Files tab for the individual fake book file WITHOUT deleting any pages I may want to see later for some reason.
 
What I did was to offset the Page Order in Files for the individual fake book to account for the discrepancy. In the Page Order field under Files for The Real Book Vol I PDF in my library, the page order appears as 1-512. I changed it to read: 14-512,1-13. That puts PDF pages 1-13 at the back of the PDF and in effect makes MSP bring up page 14 when you enter page 1 for look-up purposes. The front & rear covers & index pages are at the back and can still be accessed through page turns or entering the last 13 pages numbers in the range (499-512). 
 
Is it what I really want, no but it is manageable and my Songs list doesn't have 4000 extra entries I didn't want in the first place.
 
Thanks!!