you can keep them together, however you have to understand the risk. Chickens can harbor a parasite that causes Blackhead disease. Not all chickens have it and not all areas have it, but you don't know if your chickens have it unless you have a turkey or peafowl get sick from it. If you decide to keep them together keep a product called Fish zole on hand, it treats the Blackhead, it is a fish med but the ingredient is the same. Also keep in mind that at 3 months old the chickens if aggressive can be mean, or the peachick could get bossy with the chickens... just keep an eye on them and see how they interact, if all are good tempered and raised together you could be fine. Making a separate pen would be ideal, but I know that is not always an option.
