I mean if it’s a BP it doesn’t necessarily have to have a trigger box as the BASE- which I highly recommend against in this case. I’d have two volumes as children of a scene node- that way it doesn’t have a hierarchy. Make sure they are siblings, NOT parented.
Then you should be able to do two separate events on start/end Overlap? It SHOULD work. I haven’t tried it myself- I usually just use the level blueprint as I’ve never needed anything like that more than once in a project, really.