Another detail that might make your life easier is using an EXTERN variable.
INIT
ITEM:__Me
EXTERN STRING:%trigger="ShowTracks"
EVENTS
EVENT Disappears
ON
OnGlobalEventCleared(%trigger)
ACTIONS
SetVisible(__ME,0)
EVENT Appears
ON
OnGlobalEventSet(%trigger)
ACTIONS
SetVisible(__ME,1)
Using Extern will allow you to change by which trigger it is affected by when giving the track its scripts. So each characters tracks can be activated independently.