The reason you offer oyster shell with All Flock or Flock Raiser feed is because the OS isn't already in it. OS is already in layer feed. OS is not protein. I use layer feed because I have all laying hens, however, I'm switching to an All Flock based on great advice I have read on this site. To increase their protein intake I give a few meal worms every day, plus their run is so big, and under apple, pear, plum and pear trees, they have lots of free range bugs.Thanks for the advice! I'll look into getting a different feed. They do have access to crushed oyster shells in a separate dish. Do those contain protein? I thought it was just calcium. Huh. Anyway, I'm not sure about feeding them meat. Would meal worms and unsalted sunflower seeds work as well?
I personally don't feel your problem is with the food, but with Raven. It just matches my challenge with Rosie so well, and I worked with Rosie for a long time.
It's so hard to say. I would separate them one at a time, but not Sunshine. I know people are advising on food, and I don't know what to say about that. It has never been my issue, and you say you give treats only 3 times a week. That doesn't sound like too much, unless it's enough to be in there for several days. I know right now I'm having a nutrition problem because my apple trees are dropping apples. The food is not being eaten as usual because they love the apples. I have had so much to do lately that I haven't raked up all the apples, but I must do it soon. Like tomorrow morning. 
