Two Out of Control Hens... Help!

Iʻm currently stuck and Iʻm not sure what to do next. Any helpful advice works..

I have two Rhode Island Red hens (siblings), two White Leghorns, and three Barred Rock (the Leghorns and the Barred I got them together, probably siblings).

Lately the two RIR sisters have been bullies... One of em, the biggest out of the two, her name is Big Red. Sheʻs the bully hen. Her sister, Little Red, is the mean hen. Big Red will pick on her sister a ton but they are inseparable. I gotta keep them together or one or the other will freak out, cluck and call for the other until they're together. Big Red is such a bully hen that she has begun to pick at her sisters back feathers, and eats them. She has even started to disturb her sister from egg laying and Iʻve caught her eating Little Redʻs eggs once or twice. But Big Red is soon mean! Little Red on the other hand, will not fight back her sister. But to the other hens, she will peck and chase them away. Big Red will also do the same, but with more consistency. The other hens will do anything they can to stay away from them or get out of their way, but sometimes running away from them triggers Big Red to chase them.

I want them to all get along but Iʻm not sure what else to do.
-I have pinless peepers on both hens, but it only worked a few days until things went back to normal; being bully hens. Iʻve separated the RIRʻs from the rest of the flock, but this has only made things more worse for Little Red because sheʻs taken the beating. Since then, she's bald on her lower back. Its regrowing, thankfully, but Big Red has still been picking so much it grows sparsely.
-I have tried putting the RIRʻs in a pen within the original pen, but the RIR still bully each other....
-Right now, I have Big Red in the pen within the original pen by herself, and Iʻve left Little Red outside the pen entirely to roam freely. I hope to have her feathers to regrow and eventually learn that she can be without Big Red. Little Red can still see Big Red but she's outside the pen and canʻt get in. She has all the freedom in the world, but she chooses to stick around the pen.

Iʻm hoping this method works, but Iʻm doubtful. I will eventually let Big Red out on probation and if she goes back to doing what she does, then back into the little pen she goes.

If anything... I was considering culling the RIR or giving them away to a friend.

 

They eat a poultry feed by Nutrena Country Feeds All Flock Feed. They often get chicken scratch and leftovers from the kitchen, which is usually salad greens, papaya, cooked rice, and sometimes leftover scramble or hard boil eggs from breakfast.
Should I instead give them a game bird feed with their regular feed? Maybe cut out the chicken scratch and replace it with game bird feed for scratch?

The RIR make 1 year. And the other five (Leghorns & Barred Rocks) are still quite young, I believe they are 7-8 months, they should be laying soon.

As of late, Iʻve been working on a feral cat problem. Theyʻve killed some of my chickens and still bother my chickens to this day. So Iʻve been trying to trap the cats with a cat trap and Iʻd send them off to the humane society. Thereʻs so much of them around my bf said **** it and has begun shooting them with pellet guns. They never seem to die though because they always come right back.
So with all these darn feral cats around trying to eat my birds... Iʻve had to keep them in their pen most days. I do however let them out to stretch their wings while being supervised. At the very most, Iʻll let them go for 8 hours or more. But thats not everyday. Usually they get 3-5 hours. Right now, Little Red is out and about by herself. I feel bad for her getting beaten up and stuff... so I leave her out. She is temporarily sleeping in my garage with the dog.
I keep a couple of perches up in the pen, I think I need more. Soon Iʻll be adding more nesting boxes. Right now the RIRʻs are temporarily using cardboard boxes for laying. They always have water. They always have feed in the feeder. And I like to keep a vegetable in the pen for picking, its usually cabbage or lettuce. Still experimenting with other veggies.

 

UPDATE:

Iʻve been keeping the RIRʻs separate from each other so Big Red canʻt pick Little Red. They have been taking turns in the pen with the flock within their own little pen (they have their own cage within the entire cage). Tried Little Red with the flock without Big Red on her own without the cage, and she will go and chase after some of the hens and pick at them. The hens run away, trying to maintain the space between them but Little Red will still close in the gap and continue to chase and pick the other hens. So I separate her again. Big Red will do the same without the cage, but it seems more intense.

Nothing has changed, so I will be giving the two away to a friend who has other RIR in his own flock. He will try them out and see what happens. If not theyʻll probably be culled.

On the other hand, I donʻt think I will be getting RIRʻs again for some time.