I keep bantams and standards. They'll quarrel, mostly what I see is pecking order. I have some bantams who are older than the big ladies and some who are younger. The younger bantams are more weary and make a wide berth on the big ladies, cause 'respect your elders or get an eye picked out' as the old saying goes ;D but then on the other side of the coin my OEGB hen whose older than 85% of the flock runs around like she owns it and when she walks up to the treats everyone minds their manners, even the EExRIR mix who is 6 times her size! Since your big ladies are higher on the pecking order the bossing and bullying may be more apparent or be a little rough (big ladies are built to peck big ladies in my opinion, so when they peck a small lady it may be a little rough!) But my flock is fine. They all get along except when someone goes broody, same with my 4H friends flocks! If theres nothing really wrong I personally wouldn't try to fix it I guess? no constant bullying it anyone getting chased away from food so much they're skinny? pecking order usually keeps fairly fine order in my experience, monitoring should happen when adding birds or subtraction of birds, as pecking order can be disturbed. It *can* be a newbie mistake to mix bird sizes improperly and some birds can hav bad attitude compared to others and that can throw a wrench into plans, but in my opinion your flock sounds like it's coexisting well, no fighting? I wouldn't worry too much? : )