[Whitelaughter]

The link between identity and CelForces has always been a bit messy in IN: and the simplest way to house rule is to say "the Celestials themseleves don't know".

But for this specific example, it's easiest to assume that the Song is creating a very tenuous Vessel that the performer inhabits; because it is so minor, it can't protect the performer's Forces, but does allow access to places that the performer cannot go (extreme example, in GIN is suggests that if a mortal dies while projecting to Hell, they will be stuck there!)