You really want to watch her and make sure she is not getting trampled by the others. i've had this happen with a weak chick. Didn't notice it was lethargic and it was sleeping a lot and then getting stepped on. By the time i pulled it out, i think it had suffered internal injuries, because it didn't survive.
You have some great suggestions here with the polyvisol (without iron) or some sugar in the water, and the mashed food. Don't worry if she doesn't eat that much, she still has the yolk sac for nutrition.