Eating eggs is very tough to stop. We occasionally have egg eaters, and in the really tough cases, we end up getting rid of the bird (usually by selling it).
I’ll recommend
1. no treats, only feed. If you can, give them a higher protein feed (such as an all flock). If you must give them treats, then use their feed as a treat- wet it down to a batter or oatmeal consistency, sprinkle some seeds or fruit bits on top- they will devour it and still get proper nutrition.
2. If you don’t want to give them a new feed, you can up their protein by using canned or boiled meat - just watch the salt (low/no salt for them bc too much can be harmful). You feathered omnivores will devour any animal protein. Fish food, or dry cat food or catfish pellets used to feed pond fish can all be used a pinch, but not long term, and only as supplement, not as main feed.
3. Collect eggs frequently.
4. Use A LOT of fake eggs in the nests - each of our nests have 3 fake eggs in them. Wooden, or ceramic, or even plastic Easter eggs (filled with sand or some kind of weight), or golf balls all can work for your needs. They peck, but get no reward.
5. Inspect beak or the birds to try to determine which ones are the egg eaters. Yolk on beak is s clear sign, or dried raw egg on their feathers.
Good luck.