We did that a few years back...we raised Mary (Queen of Scotts) and Marie (Antoinette) for the holidays. (We ate Marie at Christmas, too on the nose for Mary, who was eaten Thanksgiving).
It worked well within the chicken flock. I was more of a newbie then, and since I've learned that turkeys are beneficial to chickens providing resistance for Marek's from the lesser turkey virus. However, you can pass blackhead to turkeys from chickens, which is much more of a problem for turkeys. But then, our chickens were healthy with no blackhead, so we had no problems.
It was fun. We shoveled tons of feed into the turkeys, so if you are doing this for cost effectiveness for the holidays, even for organic turkey prices, think again. I also found the turkeys to be massively more messy than the chickens, so plan for extra shavings.
Free ranging was fun. The two turkeys stuck together and did this really incredibly beautiful synchronised bobbing as they foraged. We used to stand by the windows and hold up rating cards for fun.
But it was a great project for the kids, provided (pricey) but good meat for the holidays. Turkeys and chickens free ranged with no issues.
My experiences.
LofMc