You *need* to make sure that she is eating. If an overweight/stressed cat (or sometimes any cat) does not eat for even 48 hours...liver damage can result.

I would get her out from behind the washer and put her in an even more confined space by herself (smaller room, walk-in closet, even a large cage) where you can monitor her eating. If she's overweight at all, there is a definite risk for hepatic lipidosis. It is not a death sentence, and is certainly reversible, so please don't let my comments panic you. I just want you to be aware of this possibility.

I would also suggest getting some Feliway (or other cat pheromone product) and spraying it on her bedding or in her surroundings. She sounds like she is the most sensitive soul of your foursome and probably needs some special attention during this stressful time.

Let us know how she does!