How can she be Sonja and Selma Telse at the same time if the entire show is in a shared universe.
Brooker has never said all episodes are in the same universe...that's just a fan theory, although the Netflix episodes have made it less plausible that they are. Formerly RIP_Matthew_Abaddon.
He did confirm the theory in a reddit interview.
There isn't anything to suggest that they're in the same universe.
Look for the trivia from Season 3 episode 3