Chickens may start eating eggs due to a deficiency, or because one gets broken and tasted. Chickens keep eating eggs for the same reason we do, they are delicious! Some people buy/build roll away nest boxes. I have heard of filling eggs with mustard or plaster. I have heard to people breaking them with ceramic eggs. I broke one hen from eating eggs one time by keeping the eggs collected out of the box she went to to eat and keeping hard, wooden eggs in there instead for two months. She eventually stopped trying them to see if they would break and I didn't lose any more. I would still occasionally see beak-tip sized holes in the shells from time to time, but none were consumed. I hate to say this, but it may be that the whole flock has to be culled to stop it. It wouldn't be right to rehome them. Any new birds that you get will learn it from the others. Maybe you can tolerate the behavior, but I couldn't.