My coop is a barn that also contains rabbits. However, my rabbits are in raised wire cages and we keep the chickens from roosting above the rabbits so the rabbits don't get pooped on. If you search on here for the same topic, you will find that it has been discussed many times. Some people have combined the two just fine and others have had problems. Rabbits can chew chicken feet and chickens can peck rabbits. A lot of it depends on your specific animals. There is also the issue of rabbits living in chicken feces, which increases their risk of pests and parasites. If you are concerned with the nutritional balance of their feed, there is also the logistic issue of ensuring the rabbits eat rabbit food and chickens eat chicken food. Personally, I prefer to keep them separated even though I have them in the same building.