Too funny..,How old are your girls? Those young'uns like to go out and play and leave their eggies with gramma....My first broody was a year-old black Ameraucana, by the end of the summer there were 3 black Ams fighting over the nest boxes. Strangely enuf, some of the the black Ams still laid while brooding. Mine started when i had to shut them up on the days i worked cause it wasn't dark enough by the time i left for my night shift to get them to go back in the coop.
I had two Blue Orps that were really broody at two years, but my buff orps never sat. Neither did the blue or red black or mixed color Ams. I lost all my good broodies to a fox earlier this summer, but one of the black Am daughters, who is two yo, is looking real promising, she pecks the crap out of me when i collect eggs, and if she gets a half dozen or so she won't let the others into the favorite box.
I picked my breeds specifically cause they brood (and lay pretty eggs). Believe me, if i had a good broody-girl, i would never mess with an incubator again!
lynn