We had below freezing temps here (in SC no less!) and I took a few eggs that were freezing cold and test incubated them. They hatched yesterday! The hens laid them in about 25 degree temps and we didn't collect eggs until late in the day, so they had been sitting out for hours. My experiment/test worked, so you may want to give one or two a try and see what happens.
I didn't realize you had eggs in already. Mixed 'mutts' as I call them, tend to be some of the friendliest chickens I had. And, it's kind of neat because they will 'imprint' with you if they see you first after they hatch. I have several game fowl I hatched that will come sit in my lap if I am out in the yard.
Great! I just went out and there was one egg in a nest and it was still warm. There's another hen on the nest so I'm going out in a little bit and grab that one too. I guess it wouldn't hurt to add one day after the main batch was set would it? I won't add any after today though. Thanks again!