We have 41 chickens in our backyard coop and 14 across the street.
We added 6 Bronze Turkeys at during the chick/pullet stage (all chickens and Turkeys were days/weeks old). We built a second (attached) coop structure for the Turkeys because we thought that they wouldn't want to "live" together and the door to the chicken coop was very small for full grown Turkeys...needless to say, they hardly use the other coop and manage to squeeze themselves through a hole that is only 7" x 10"...it's quite hilarious.
We have discovered that they are very social and really enjoy being with their chicken friends. When they are out free ranging, the chickens are often found laying in the dirt and leaning on the turkeys...turkeys don't mind at all.
Only issue I would caution is that some areas and breeds are prone to Blackhead...while chickens aren't susceptible to this but can be carriers. If a Turkey gets this disease there is no cure and the Turkey will likely die. We started with 8 turkeys, two died for unknown reasons and one died from a fox attack.
The downside is that these Turkeys and chickens eat sooooo much food (even though they free range)....When we harvest, we are going to have the most expensive Turkey Dinner ever...LOL