I agree, I don't think she will fall for having chicks put in with her unless she has some hatching under her as well. She might even attack them since she would be guarding her nest and see them as a threat.
I had a broody that hatched some eggs herself and I had hatched some in bator because she originally had too many to keep under her small self. So as the chicks in bator hatched, the same time as chicks under mom hatched, I put them in with her and they ran right under her wing as she lifted it.
You could get some fertile eggs and put under her.
How long has she been broody? If she is eating and drinking she can stay broody for longer periods. They hatch peafowl eggs by putting them under broody hens that they keep broody for up to six months by always taking the eggs away just before they hatch and putting more under her - kinda cruel if you ask me but point is that being broody for more than 21 days won't kill her if she's eating and drinking.
BUT....with all that said, my first broody, a young Buff Orp, died because she sat on a nest of nonfertile eggs for about a month and would not get off the nest to eat or drink no matter what I tried. I didn't realize she wasn't eating or drinking till she was too far run down.
You could take the broody and put her in a pen without a nest or eggs as suggested.
