Thank you for your input TwoCrows, I did watch them for quite some time yesterday and the other two girls don't seem to bother her when I am out there. What I did observe is she eats constantly while the others run around and scratch. And when all three of them are running around the yard, they stick close to her, one on either side of her as if protecting her. I don't sense any hostility, in fact the two big girls peck at each other and not her. In their established pecking order she is last, always the last to go into the coop at night and last to get out in the morning. I think she may just be slow, which is fine with me, I just don't want her to have something major wrong with her. If she doesn't lay eggs it's not that big of a deal, I just want her to be happy.