Welcome. I'm wondering if the current behaviors you are seeing are a result of your flock re-working the pecking order after the loss of one of your birds. Is your coop and run large enough: minimum of 4 s.f. in coop and 10 s.f. in run? You might add some stress busters: a hay bale tunnel: 2 bales on bottom, with space between them, and a third stacked on top. This makes a nice multi height place for them to play, as well as a spot for out of sight areas. I like to put a piece of plywood over the bottom 2 bales to span the gap just to make the structure more stable. Deep litter in coop and run will give them other activities to engage in instead of picking on each other. Bored birds can cause a lot of trouble. What is the protein and mill date of your feed? Feed over 6 weeks old is breaking down in it's nutrient value, and if they are lacking protein, that can cause aggression. Too much heat can also do so, though that is not likely to be a problem now in Northern Hemisphere. But... have you been keeping your birds in b/c of cold or rainy weather?