I never figured out a way to do it, unfortunately. I'm no coder though, so I'm sure it's possible for someone more knowledgeable and skilled than myself.
Nope. I think it's not possible with this system, and would require something custom coded into Ren'Py to work with that scenario in mind. I gave up trying to find a way to do it, since I don't know how to code.
I managed to get someone to fix it for me, enabling me to change the music and leave it up to the player, whenever they want. I'll post the code when I get a moment
