Can I do anything about rejection?

I would try again, I don't know what time of day you tried to put the chicks with then hen but it should be done at night, I usually wait until around 11pm when its full dark and they have been to roost for a few hours.. Slip the chick behind her so she cannot see it and under her, do it quickly with as little as fuss as you can and remove yourself.. She shouldn't fuss with it .. Try an be out early in the morning ( I mean super early) and see how she does with it.. Remove it if it looks like she hasn't accepted it, maybe remove one of her chicks to raise with it..