Demon King Style Boss Music

I’ve been working on a short FE8 hack using FEBuilder, and I’m wondering if it’s possible to make a custom boss track I’ve inserted start from a different point after the first engagement with a boss. For example, the Demon King track plays an extended intro the first time you enter battle, then all subsequent battles skip this intro. I thought I might need to use two separate tracks, but it seems that the Demon King is assigned only one song via the boss music editor in the unit placer. I don’t see any event flags for the chapter, so is it just hardcoded?