I agree, don't separate her. Chicks need to be with their peers for support and the competition for food stimulates a weak chick to want to eat.
Give them all a treat of scrambled eggs, or crumpled tofu. Those are easy to digest and are perfect foods for chicks.
The best thing going forward, since you've taken emergency measures, is to make a "weak tea" with their drinking water and a few drops of Nutri-drench. They all can drink it with no problem.
Since the breeder is certified NPIP, I would hold off on the Corid since it blocks B vitamins that could be helpful to this recovering chick.
Give them all a treat of scrambled eggs, or crumpled tofu. Those are easy to digest and are perfect foods for chicks.
The best thing going forward, since you've taken emergency measures, is to make a "weak tea" with their drinking water and a few drops of Nutri-drench. They all can drink it with no problem.
Since the breeder is certified NPIP, I would hold off on the Corid since it blocks B vitamins that could be helpful to this recovering chick.