@Grozours:
Remember when he killed that guy with the wires?
Behind that guy's real body that was underground a "creature" that somehow resembles an angel's high tiered battle form appeared.
That "creature" then told the wire guy that this is his real body and the body up top saving the princess is a puppet-like body he controls.
Also remember when he deployed the Soul Tier Angel the first time to "save" his human body?
He found it weird to look at himself while looking down from the Soul Tier Angel's perspective.
So the current "human" Mu Siyun and the "Soul Tier Angel" are like dolls that his mind is connected to and are moved by him.
Or see it like a computer that is connected to other devices like headphones, micro, camera, loudspeakers etc. to interact with the surroundings.
His main body (the battle form like creature) is the computer and hiding himself.
All the other "bodies" (silver haired Soul Tier Angel and "human" Mu Siyun - maybe even more later) are those devices the computer uses to interact.
So he is connected to all of those bodies at the same time.
He experiences his life as "human Mu Siyun" at the same time as his life as the "Soul Tier Angel" while he hides his real body in another dimension or so.