You can put the chicks in a wire cage in the coop so they can get used of seeing each other. During the day you can let them together for a few hours then at night separate them. If your coop is big enough, let the chicks out with her. If she doesn't like the chicks, the chicks can run away from her since the coops so big. You can also wait for the hen to go broody and maybe she might except the chicks better? Good luck!