adding guineas and ducks to the flock

[big faulky]

I want to add ducks and guineas to the flock. I understand that there may be some pecking order issues. I have 5 month old chickens. I plan to raise the ducks and guineas in the same pen until mature, away from the chickens. My main concern is disease/parasites. At some point all will free range together and I don't want to add if it will cause sickness. For example, I have read, there is a risk keeping chickens and turkeys together because chickens could eat Turkey poop and increase the chance of getting blackheads disease. I believe that is what I read. Anyway, I hope I posted this in the right place. This site has been an amazing resource for me to get started with my chickens.
Thanks
Cole

 

[TLWR]

I have free range ducks locked up at night. I bought chicks last night at TSC with plans to let them free range with the ducks in a few months.