Plucked Chook!

[MrsMacChicken]

I have a very small flock of birds which I will list in order of rank from top chook down. Gold Laced Wyandotte, Silver Spangled Hamburg, Crested Cream Legbar #1, Crested Cream Legbar #2. According to my husband...fatso, seagull, and the Pterodactyls!
I have listed the in order of rank deliberately. The GLW and SSH were chicks together and are bonded. The CCLs are sisters and were introduced to the flock when the original two were a year old. They share nesting box and roosts but after a year together still free range mostly as two pairs. All obey the top chook.
Now comes the problem. Lowest ranking chicken is literally hen pecked by her sister. She has a bare bum and a few neck feathers missing. The CCL #1 is definitely the plucker. She has also has a go at the smaller SSH who stands up for herself very well.
Although CCL #2 appears healthy and is laying well, she looks awful!
I have tried isolating CCL #1 from the flock but on reintroduction she starts the behaviour again. I have sprayed the plucked bird with purple spray to deter the plucker to no avail. I have increased the protein in their diet as the plucker eats the feathers.
How can I stop this behaviour or protect the underchicken from further abuse? Help!

 

[50-45-1]

https://www.communitychickens.com/feather-picking-and-pinless-peepers/
if you know the feather picking hen, get a pair if pinless peepers on her and it will stop it. above is a nice article.
i purchased 24 peepers and the tool to put them on and with the help of my daughter to hold the chicken, it was easy.
my feather picking hen wore the peepers for 6 weeks. when i took them off she forgot about the habit.

 

[MrsMacChicken]

Thanks 50-45-1. I have just ordered some online

 

[chickens really]

What are you feeding daily? Protein percentage of feed. Any additional snacks daily? Size of Coop and ventilation.
Behaviour definitely can be caused from management issues.

 

[MrsMacChicken]

Only one out of the four is a plucker. They free range and get high protein pellets as well as supplements of mealworms and kitchen scraps which include meat. I have discounted protein issues as even with an increase in what they already get the behaviour continues. No boredom, coop, or ventilation problems as they free range. They only go into the hen house to lay and at night. It is very well ventilated with side vents as well as open door and heat extractor on the roof. Oh, and a solar battery that runs a fan for those hot nights.
No management issues here, as these girls live a life of luxury lol.