for what it's worth... I've just introduced three bantam to two wicked old hybrids.
It's taken two weeks and all has settled down. The lavender aracauna isn't laying yet (but she may just be a bit young ) everyone is eating (the layers pellets) and all pecking has stopped.
here's what we found helpful.......
when we kept seperating the two groups we found there was less aggression if let the biguns out for a wander and put the littluns in a spare run on the grass (we used a fireguard

) then, put them all back in the main run at tea time where they preened and fought til bedtime.
we used old fridge and cooker racks and sticks to make perches, hidey holes and tunnels with food in.
we put food and water stations everywhere in the run.
we only put treats in at teatime...and then only ones with distracting value (cabbage on a stick, corn on the cob) so that they really had to eat their pellets (they reckon chooks eat 85% of diet in the early morning)
most importantly........the more we stayed away, the less they fought.
when we watched from the house we noted that the littluns kept their heads down and were mainly ignored, when we went out there all hell broke loose.
never intervene unless blood is drawn.
took me the whole first week to learn not to try and protect. as soon as I toddled off....things got better.
promise.