It sounds pretty normal as far as pecking order. As long as there continues to be no blood or other injuries I would be fine with it, as long as the Cochin can still eat and drink without too many issues, even if she has to wait a bit.
You have enough space indoors for all the birds, but if a bird is a bully they may be a bully regardless of the fact that you meet a suggested space guideline.
I would add more clutter to the outdoor area, even if just temporarily. How old are the chicks? How old were the chicks that were...