What happens if a mother broody chicken won't accept a baby chick?

I have a buff orphan, and she has been broody for 2 days. I bought a baby chick and tried slipping her under her, but she won't let her stay. She started pecking her when she first saw her. Will the mother hen change her opinion and let her get under her? Is there anything we can do to help. Is there anything we should do for the next time the chicken gets broody?