Is this currently possible? I haven't been able to find it.
If it isn't that's a huge red mark against the product. Using local groups would be painful for large deployment of users and policies.
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When in doubt, Script it out.
Once you have added an AD authentication server, click on Import. It's a small blue icon to the far right of the authentication server you have just defined. The documentation needs to be updated to indicate this. See attached screen shots.
Once you have added an AD authentication server, click on Import. It's a small blue icon to the far right of the authentication server you have just defined. The documentation needs to be updated to indicate this. See attached screen shots.