Are the shells thin? Is there a lack of calcium in there diet? When we lived out west, we fed oyster shells to the hens to prevent calcium deficiency. Mom would put a dead animal in there pen for them to peck on, so they would leave the eggs alone. sometimes it seemed to help.

I stumbled on a new observation, when I recently merged two flocks together. I moved a larger flock (with rooster) into a smaller flock, with no rooster. So the smaller flock believed they owned the nests. I've not had egg eating from either flock, until I merged them together.

After watching the boss hen, in the old flock in the nests, I realised she was trying to turf out the new birds. She didn't want any birds (apart from her sisters) using the nest. The egg eating would only happen in the morning, if I got their food to them late. The eggs laid in the afternoon were never touched. And it was always the smaller eggs of the new flock eaten - not the larger ones.

I've come to the conclusion, this boss hen is asserting her genetic progenies survival. She only wants her eggs to be in the nest. So I wonder if because there are new nests, and so many hens, if they are vying for who should own the territory? New digs, means new territory to establish in the heirachy. You could try putting a nest box inside the run, and see if any eggs get laid there, or eaten? I noticed eggs laid on the floor were never touched - only the ones in the nest.