Funny thing .... your description actually pretty much describes what you need
import all 3 tunes ....
In each layouts event sheets
Event
on start of layout,
sub event audio tag "level1" not playing (inverted)
Action
audio play tune 1 tag "level1"
Event
Level finished (some event determining that the level is finished)
sub event
audio tag "level1" is playing
action
audio stop tag "level1"