I had 2 dark brahmas go broody, 1 kept it up for the better part of 3 months. They began in January, and I didn't want to put eggs under them that soon. I gave both of them 6 eggs each at the beginning of March. They were consistent in setting on the eggs, but both froze them on day 12 by going to another box. I'm in central kansas and we had a major cold spell, wind chills down to -20. One broke her broodiness after that, but the 2nd is still at it. I have a naked neck that has gone broody, so I ordered more eggs to try her out. I put 2 eggs under the dark brahma, and 2 under the naked neck. Within 6 hours of putting the eggs under them, the dark brahma had moved off her eggs. I put her 2 under the naked neck, and she is on day 14 of incubating them and they are alive and well. The dark brahma is still brooding, but won't set consistently on eggs. Some girls just don't make good mothers even though we want them to. Maybe isolating her to a brooder pen would help, I am new to this, and spent a good chunk of money on the eggs that the first 2 girls froze, I don't want you to do the same thing.