I do have a separate pen and coop for my call ducks because I have a drake. Drakes can really hurt chicken hens, so you have to be very careful when keeping them with chickens. If you get two females, you should be fine keeping them with your hens, though ducks are messier than chickens so be aware of that! I can't help you with how difficult integrating them together is, though, sorry. I gave Crashie a bath this afternoon and shredded up some grass for him to swim after. He went nuts! I was afraid I had put too much in and would have to clean out the tub afterward, but he ate almost every single bit of it! I was surprised after the trial run with grass in his little dish. He didn't seem to want to eat it out of the little dish! Also, I finished a grazing frame today for the girls and planted some grass underneath it! They should have fresh grass to peck at in their yard after a week or two! Yay for getting things done!