Brooder is not good together as ducks are slobs.
Adult life - our ducks, big chooks and normal guineas live together without any major problems. Sometimes the guineas act like idiots, as they are prone to doing. In the coop/attached run, the duck pond is a sunk in pond with a series of ledges so the chickens can get out if they get in. Also, the pond is fenced with a low fence - ducks just hop right over, the big chickens who are sane and normal don't bother (what's fun on that side, nothing), the barred rocks hop over some, realize it's the evil water and run out, and the chicks can't get over the fence really well usually until they are big enough to be able to get back out of the water also. I figure they COULD get over earlier, but none of them have ever tried.
However, given as DH brought home MORE ducks, I think he's going to be building a new duck coop for the ducks to have their own home.
The jumbo guineas live with the peafowl to everyone's joy and delight. They were with the chooks and just being weirdos, one night they went to the peas roosts and we found all of them all cuddled up together. Ok, if you insist. I think the peahens think the jumbos are their children.