I wouldn't take them away, either. I'd let her raise them like Racuda did. Then sell them. You can sell started pullets, easy. Lots of people want them. Started cockerels, not as much, but depending on the breed, you may still sell them. I've sold some full grown roos.
If I wanted to hatch eggs and sell day-old chicks, I'd use an incubator. More chicks at once, to make it worthwhile, and no upset, heart-broken, freaked-out hen if you took her chicks away right after she sat on them for three weeks. I know some people do this, but it just feels wrong, to me.