Redmine

Excuse my post if this has been answer previously. I'm running Redmine 2.3.2 and have noticed something about the private comments

There seems to be no ability to add a watcher to share private comments with other users. Is there a plugin for this? Is a plugin the correct way to implement this functionality or would a patch be the correct way?

A scenario could be a private issue has 5 watchers. A new comment is created and only to be shared with 2 users. Those users may or may not be part of the issue.

Thanks for any help or direction on this.