[reggoboy]

My recommendation is not to import the file from outside MobileSheets, and instead select the song on the library screen...

Aww, man. I thought that I had discovered a secret and huge productivity boost! I do a lot of editing of PDFs outside MS and swap them in. I don't typically have the file searched in MS, or MS even running when I'm ready to import a modified PDF. But just doing Open With > MobileSheets not only launches the app and finds the file, but initiates a Swap. Genius! 

I just did a bunch of experiments. It does bring up the Import Settings dialog that shows that it intends to add it to the Setlist if the Setlist is open on the screen. So I guess that makes sense and gives you the chance to de-select that. 

With that in mind, I think I'm going to keep using the Open With feature in macOS for now...

Thanks!