Fuck off dude, I'm allowed to tinfoil from time to time. No need to be a dick about it.
The story literally starts out with Edward talking to a voice in his head and perceptions are pretty fucked up for a schizophrenic. What if the interactions he witnessed didn't happen exactly the way it's presented? What if that girl who was getting harassed by Neil Swanger was just a random girl that Edward "manifested" Elsa from. In fight club, there were many instances where Tyler acted as a second party but it turned out that it was the Narrator doing those things and was interacting with those characters. None of the other characters picked up on the fact that he was schizo. All I'm saying is maybe it's something similar. Just because we see Elsa talking to someone or doing something, doesn't mean it actually happened exactly that way in reality.
I'm just saying it'd be an interesting twist. It's no question that Edward's mental instability is a major plot element, so what if we're seeing everything from his warped perception of things?