if ur baby was the same age she would probably adopt it but more than likely it will be an outsider to the older chicks and be picked on or pushed out and starved or stomped. u should seperate her till the others hatch and give her, her own brooder till the new ones can join her.
babies don't need to be in the hatcher once they r fully fluffed, they should move to the brooder asap with a heat lamp once they r up and about, waterer w/ marbles or rocks(to keep from drwning) and feed. they can go without till their yolk sac is absorbed as many as 3 days but mine always eat right away or first 24 hours after hatch. i use a 1 qt canning jar waterer with a quail base which don't need marbles or a chick base which does. my feeders r long plastic chick feeders with lids to keep them out or flip over 1qt canning jars with metal or plastic feed lids.
hope that helps,
silkie