[chrisss]

I suppose my question can be rephrased like this: if I select 2 tunes to "batch edit" - with the goal of making sure they share 1 overlapping genre  - won't the end result be that they share all of their genres?

I tried a test with a couple of tunes and thought that was the result I was seeing.

I think that's how "batch edit" of songs works too, tho I'm not 100.0% sure.

But there's another approach - edit the Genre itself, rather than batch edit songs.  Like this:

Tap on the Genres tab at the top.  MSP shows u all the genres in the library.
Tap+HOLD on a Genre that you want to edit. MSP will put boxes to the left of all the Genre rows, and put a tick in that Genre's box.
In the menu at the top right, tap EDIT. MSP will show a split screen - all the songs already in the Genre on the left, and all the songs in the library (FILTERED) on the right.  Be careful not to have filters active when u do this, or you'll only see the library as filtered by the active filters - not the whole library.