Update:
I really don't want to worry about anybody getting too bullied so now I'm thinking about maybe 1 standard cochin so at least it might be slightly bigger than the others. Would that be any better? I think there's a breeder in northern Washington according to the PNPA's breeder directory with both standard and bantam (i don't know how often they update) and an australorp breeder around there too. how close in age do they need to be? Am I better off getting chicks from mypetchicken.com?