I wasn't very detailed in my earlier post. I'll close that gap now.
Some time ago (it feels like 18 months) the vet took a look at Peggy's liver (as in surgically - he opened her and looked at her liver) and made a confirmed diagnosis of hepatic lipidosis, noting her liver had fractured and she had internal bleeding.
It was my fault for giving too many treats because the hens loved treats and I loved seeing them excited for meal worms or bread crusts or whatever.
Back then, they were on a 17% protein blend for layers, made up of "mash" (shaped like a crumble but with nutrients for layers) and grains. Perhaps Peggy was selectively eating her favourite grains and ignoring the mash.
The vet said
- High protein pellets 24/7
- Foraging
- Cottage cheese
- DMG
- Milk thistle
- Biotin
- Choline
- Almost no treats
- If I must give a treat, it had to be fresh food like lettuce, carrot, apple, tomato etc
I feed the four supplements mixed into a nightly mash (ie pellets softened with water). I give it in four bowls, one per hen, with maybe a quarter to a half teaspoon of cottage cheese on top. They come running and the bowls are usually empty by roosting time.
Peggy has thrived. They all have.
Until she sat for four weeks recently. While she was sitting she did not get the evening dinner. She ate regularly and maintained good habits, but she was zoned out at dinner time and I didn't want to mess with her body clock by getting her up again. Her poops went black. I presume her liver bled again. She's ok again now that she's been back on the regular diet for a few weeks.
Mainly for this reason, I won't let her sit in future. (But also she killed the chick and now I don't trust her with hatchlings.)
That's the full story of Peggy's liver.
For your hens, I think what you're doing sounds good. But I would be tempted to let them fill up on chicken food whenever they wanted to and I would keep the chop to a minimum.
Would it be possible for your new coop to have two apartments? One apartment for the retirees and their diet, the other apartment for the layers and their diet? Still the same flock while foraging around the garden, but living as next door neighbours in the coop. Friendships would stay strong but there might be fewer scuffles at roosting and better dietary outcomes.
(And I share your fears about corn, mealworms and pasta, your friendship for Bob, and your pain in bringing up these thoughts

)