Okay, I'm going to use a little terminology; I know Kuma can keep up, if anybody else has questions as to what the hell I'm talking about, PM me.
So it sounds like you have characters who are using a restricted resource (tokens) to give them increased authority for proposing amendments to the fiction. Do their roles (Maker/Seer/Knower/etc) also function as authority tools, or do they have no effect? Either way, this establishes a spoken narrative in the first six hour session of play.
Players can then take notes on a 3x5 card on what happened.
Where and when do the unspent tokens get spent to add things to the spoken narrative? When is the traitor selected?
Then the players come back for the second session. They reconstruct the narrative of the first session from memory and scant notes. They then proceed to spend (refreshed?) tokens to introduce new amendments to the fiction, but their intent now is different -- they are trying to implicate others and protect themselves by piling up facts in the fiction to support their claim that they're innocent and somebody else is guilty.
I don't understand why players want to add in more details after the first session establishes the narrative. What advantage does this give them? Can you give an example?
When (and if) the traitor is chosen is pretty key. If it's at the way-beginning, this allows him to position himself throughout the whole game. If it's at the end of the first session, he'll be scrambling. If the traitor's identity is undetermined until the end of the second session, then everybody is constantly positioning and scrambling throughout the entire game.
Do I have this much straight so far, Kuma?