One of my bantams hatched two eggs, but unfortunately one chick got taken by a hawk I think. That left her with one, which I called Norris. Then the bantie (this was her first hatch) seemed to lose interest in Norris, and he was walking round the field on his own. I was lucky to have another bantam with 6 chicks, a few days younger than him. So one night I popped Norris under the bantam with the other chicks, and she either has not noticed a spare one, or does not mind. He is quite happy, and tags along with the others. Just he is a good bit taller, and finds it hard to get himself under the hen now.
Had the original bantam not lost interest, I would have left her with one chick. Sometimes they will take to another hens chick, other times not.