My question is this-- why do they all want the same boxes? I put wooden eggs in all the boxes for a hint. I went into the coop today and I had two hens in each of two boxes and two empty. If one of the girls is in the "favorite" box sometimes the others will stand there and squawk rather than use the others. What's with that?
I did have one broody Cochin that sat her nest in one of the places in the chicken yard but not until she played musical nests for about a week.