This is why I move my broodies, In the beginning I have had a broody to get off her nest---while she was eating, etc another hen got in her nest to lay a egg, then the broody got in a different nest and all her eggs got cold---none hatched. By moving them to a hatching pen---only one nest---only the broody----never had that problem again and have real good hatch rates.
Maybe if you explain that the mother hen wouldn't be able to keep her babies from freezing...no matter how hard she tried...it's tough to explain to a child of 6 that there are possible negative repercussions from doing things, just because you want something right now....at that age the concept of tomorrow can be difficult to comprehend...let alone weeks from now. They just don't get it yet. She may seem to understand....but just ask her how long she thinks it will be till she will be able to go swimming at the lake? Or something like that. There's a good chance she will be a bit confused as to how to answer....and if she has an answer, it won't be close to correct. It might help to get a calendar and pick a reasonable date for a broody to start a set and start a count down to the date. It will give her an idea of how long it will be and something to look forward to.
It wasn't the incubator that did me in, it was the dang broody hens. That and my egg source. She has show quality stock, and she keeps sending me home with too many eggs. Hence, my 2nd coop for the English Orps I hatched, well my broodies hatched, last summer.
Whats wrong with "adding a few"? I built a bigger incubator 1 1/2 years ago----only hatched a little over 5600 in the next year or so----I do not see a problem!!! LOL
