My intent was to retire my hens to the stew pot when they stopped laying. Involving my two daughters in the planning and especially in the rearing of our first chicks nipped that idea in the bud. I briefly argued my case but then realized the point of this for us was the experience and the reflection on what it takes to feed the human race.
I would announce that only a certain number of hens will be allowed at any given time, then involve the kids in buying some new chicks. When the chicks grow up, make a list of the right number of chickens to keep (letting the kids help choose), and butcher all the rest. Yes, that probably includes butchering some of the new pullets. But it's likely that some of the new pullets will make it onto the "keep" list, which will force a few older hens off the list, so they'll get butchered. But I find it less painful to think of it as "keeping Snowy" rather than "deciding to eat Goldy," or whatever the names happen to be.