I have successfully kept all of my chickens and guinea fowl together. I have 3 barred rocks, 3 buff orpingtons, 5 black sexlinks, and 3 RIR happy living with 5 Guineas.
The chickens bullied a little when the guineas were young but now those guineas fluff their stuff and push them bossy hens right out of the way....
I think the key for me was that the guineas matured faster or learned faster how to flap their wings because they learned real quick that they could get away from the chickens by flapping all the way up to the top roosting bar which is way farther then the chickens are willing to go...
Now full grow they all happily comingle in one happy cage.... I have three young guineas out in a small pen inside the large pen so far no major miss haps... even had one escape and no one bothered him.
The chickens bullied a little when the guineas were young but now those guineas fluff their stuff and push them bossy hens right out of the way....
I think the key for me was that the guineas matured faster or learned faster how to flap their wings because they learned real quick that they could get away from the chickens by flapping all the way up to the top roosting bar which is way farther then the chickens are willing to go...
Now full grow they all happily comingle in one happy cage.... I have three young guineas out in a small pen inside the large pen so far no major miss haps... even had one escape and no one bothered him.