Egg Hatching/Setting Hen Question

[Eddy Chicken]

I have a broody Australorpe that is on 6 eggs for the last 3 days. I selected those eggs based on the hens that lay them and their health, size, egg size, and laying rate.

I wanted to add another egg from todays lay for a total of 7 eggs but it is 3 days later. Can I do this and will she stay there and wait to hatch them all before laving with the earlier hatching chicks?

Papa is a Dark Brahma and the mama's are Black Australorpes, Buff Orpingtons, Rhode Island Reds, Dark, Buff, and Light, Brahma.

Thanks,
Ed

 

[ChickenCanoe]

She'll probably give up a couple days after the first hatch because she needs to get the chicks to food and water.
You could put it under there and incubate it artificially the last couple days.
A box with a light, a pan of water and a sponge if you can get the box between 96 and 100 it could work.
IMO the temp isn't as critical the last day or so because they're generating some of their own. Humidity is more critical at the end.