We currently have two 4400's along with WCS. We would like to add an additional 4400 to the group. I have read the documentation and not come across a clear cut example of adding an additional 4400 to a production group.
You would add the 3rd controller just like you did the first two. What you need to keep in mind is the Ap count because of your WCS license. Once you do the initial config for the 3rd controller, you add it in the same mobility group as the first two and add all three controllers as mobility memebers of each other and you should be good.