What I did when I wanted to hatch shipped eggs, and had a broody, was to let the broody sit on fake eggs and incubate the eggs with an incubator. Then when the eggs hatched, I gave the day old chicks to the hen.
This worked very well for me, but I did know the hen well. If you don't know how good a mother she is, you would want to supervise her closely until she is making mother hen noises and giving food to them.
This worked very well for me, but I did know the hen well. If you don't know how good a mother she is, you would want to supervise her closely until she is making mother hen noises and giving food to them.