I wouldn't mind putting her back as long as the hen will take her back and not kick her out again. Her litter mates are 3-4 days older and I'm not sure if that has anything to do with it or not. And since she just hatched I'm not sure to try and give her a drink of sugar water or not?
Try adding her back at night, the hen will be quiet then. If the others are older had she abandoned this egg and taken the others off the nest to feed and drink?