Having another enclosure adjacent to main setup, or splitting off a section with wire, can still help you play 'mix and match chicken juggling'. It will throw them off and put a hiccup in the bullying. Add a bunch of hiding places, stuff to climb up on and behind/out of line of sight, etc will offer diversion and that 'change' chickens don't like so much.It'll be difficult to isolate the worst bullies, as it's half the flock.
Course it could be that something is wrong with Daisy that the birds can sense but you cannot. Sometimes a bird just will not fit in with the flock and should be removed.