[dbrown1029]

Dave,

1) Every time I modify my source PDF in another tool (a frequent occurence), I'll always have to re-import it and overwrite the copy that MobileSheets created for me; and

That is true, if you modify the file, you have to put the updated file in the place MobileSheets is referencing the file. However, you can do that in many ways. You can literally just copy the file into the storage location and overwrite the existing file. You can change the storage location and work directly out of whatever folder you use to manage all your PDFs. You can synchronize to a cloud folder if that's easier. 

2) I will have to move my entire library of mp3's to a folder somewhere under the LocalState folder for the links to work correctly.

No, you absolutely do not need to do this. I tested your first PDF which links to C:\Users\dave\OneDrive\Music\Backing_Tracks\Besame Mucho - Bocelli version.mp3 and that loaded just fine. I just recreated that folder path on my device and the file was loaded in an external media player. 

If you add the audio file to the song in the song editor, or you use a smart button, then you are correct, you don't have to rely on hyperlinks. There are other benefits to playing the audio track from within MobileSheets as well. You just have some extra steps required to set that up. MobileSheets also supports automatically associating audio files with PDFs that are imported if they have the same name (just enable Settings->Import Settings->Automatically Add Matching Audio).

Mike

Thanks again, Mike. I am confident now that I can use MobileSheets for both of my main use-cases. And I *really* appreciate your amazing responsiveness. Just one more question: you've no doubt figured out that my primary use-case involves multiple audio files attached to a single PDF (i.e. "song"). Is there an upper limit to the number of songs that can be associated with one PDF? I have one that might approach 200 audio files.