I forgot to add this in my last post. Guineas require a LOT more space than chickens do. If they are kept in a small pen, they will be literal demons and will literally kill your other chickens. My flock is free range, so I don't have that problem.
Our guineas are well past their breeding season and they do WONDERFUL with our bannie chickens. I'm pretty sure that they're being so mean because the chickens and the guineas are from two different flocks. If the guinea flock was larger, I don't think this would be as much of a problem as it...