Here's a question: If there's multiple sessions at one given time originating from the same universe, what happens to the rest when one of them decides to scratch?

They’re erased in the exact same way- What is being reset is the Universe, Session included, so since the Sessions originated from the same iteration of the Planet that is being reset, they would’ve never started playing, and as such, would have their entire existences erased. Except these Sessions wouldn’t even have the ability to predict when the Scratch is happening and prepare for it, or perhaps even know why the Sky suddenly started to Glitch.