I am very new to chickens--less than a year---and I have a broody FBCM. She got broody all of a sudden, so I put 3 eggs under her. She stayed in the main house for about 5 days, and this stressed my other layers to the point that they started laying elsewhere. So we decided to move her and the eggs. We did so at night, but did not contain her in a cat carrier or other very enclosed area, so she was off her eggs the morning, but had chosen another spot. So I put more eggs under her and we are on day 10 of her second set of eggs.
She has already lost more weight than I would like. I get her off her nest twice a day for 10-15 minutes each time, by physically picking her up and carrying her away from the eggs, and am able to get her to eat and drink. As soon as she eats a little and drinks, she starts looking for her nest, so I let her back in, and she promptly gets back on the eggs. The beauty of a broody hen is that she is doing all of the work....I am just trying to keep her in as good a condition as possible.
You mentioned that your granddaughter was removing eggs from under her. Are the other hens getting in her box when she is out eating and laying eggs....or is she still laying??
If it were me, and my hen had been broody for several weeks, I would consider putting her in a pet carrier with 2 or 3 eggs for a day or two, giving her access to food and water, and try to find a couple of day-old chicks to put under her at night to see if she will take them. It sounds like she really wants babies.
I don't have any experience breaking a broody hen, but I would be concerned about her health if she has been broody that long and there is no end in sight for her in terms of hatching out her own chicks.