You were lied to.
Do not brood the keets with the chicks. You will be sorry later.
Keets need a high protein turkey or game bird starter. Chick starter does not have the levels of protein, lysine, methionine or niacin that keets need for proper development.
Brooding keets with chicks causes them to be imprinted. When they are adults they will not be able to understand that chickens are not guineas and they will treat the chickens the same way they treat each other. Guineas have entirely different instincts than any other poultry.
Other poultry do not understand the races and chases and attacks from behind with the feather pulling and feather breaking. The other poultry do not understand the attacks en masse that guineas also use.
Other poultry do not know how to show submission in guinea causing the attacks to keep going on.
Read the thread
Raising Guinea Fowl 101 and pay particular attention to posts by
@PeepsCA.