Lets examine that in conjunction with Griff's assertion Starborn exist in all timelines.
First, i'm going to limit it right now, to DF verses only. Then take what JB said about the NN surrounding only earth in 'this' reality and apply it to the DF verse proper. Stars are ergo outside of reality, the masks of those things are known and worn on earth, imo if the thing itself is whole, a whole star, then it's more or less an angel class being, ergo immutable by Nemesis(whom is then off our star/shadow, only able to effect what stand inside our light, Angels are outside of space/time to view it. Harry, starborn, of the stars, but mortal, mutable himself, can effect both sides as you 'cant' protect from yourself') So reality surrounds earth and those things outside of reality pierce into it in various guises depending on which reality it is, also why Outsiders look different but Uriel actually looks the same in all realities, he is the star, he went from mortal starborn to immortal star simultaneously. Basically overwriting it's old form the same way the fallen now think they are the originals but Lasciels 'closest to true form' is a 2k yr old Greek woman..
Anyway, what was I talking about?