Is it?
Just keep all dialogue checked if *event* happened ... (if it happened, your character WAS there)
And when you are under effect of Disguise, bypass that check.
> Vendors will talk to you as if they see you for the first time.
> Nobody will cause you for a cryme, bcs it "didnt happened".
> Corpses will talk to you.
> Events will happen as if you get there different way.
Its cheap solution, but it works.
