Interesting pics, but I don't think I could do that part.
I have 3 preschools that I'll be working with in April. We're doing a test hatch at home to see how the eggs from my newer hens are doing. Two hens' eggs are not fertile!!! I'm surprised. I set 3 eggs from each hen, so out of the 18 eggs - only 12 were actually fertile. Out of those 12, 10 have dancing embryos. The hatch date is March 18th.
At least I know not to give those hens' eggs to the schools. Our former roo was so hard on the hens, but all were fertile. (even for 2-3 weeks after he left!) Our new boy is a gentleman & doesn't force the girls.