The problem for the other QBs at this point...is that Romo is eligible to practice starting this week, and they've said he'll participate immediately. That may start with throwing on the side, and then progress to 7-on-7. Soon there will be very limited first team reps for others (possibly with the exception of Wednesdays). Garrett also said that Cassel will take the majority (if not all), of the 1st team reps this week.
While not my favorite course of action, perhaps carry all 3 for the next two games if able to. If one is really flubbing things badly...perhaps put another in. Inexplicably, even Weeden has performed quite a bit better in relief. Moore is an unknown given he's never started an NFL regular season game. They get to see him everyday...but if at all potentially contemplating playing him at some point, they'd have to activate him & give him at least some 1st team reps.
I think they're gonna ride with Cassel until Romo returns. Hopefully, it's not to another two losses. Given that they'll pretty much need to win the division...the Eagles game is crucial.