I have the same breed! And there's five of them, around the same age as your's. Hmmm, I haven't had this problem. So what I'll suggest is putting her in a separate living space for a bit, and after a while put her back with the others. I think it reduces their bossy role if they are away for a while. But maybe someone can give you a better solution. Also provide more feeders and waterers for the others, I doubt she can block off both.