I'd like to also add the ability to mark staffs if they're in your group because sometimes (they're usually group leaders - not all though) they're hosting a group activity and somtimes it'd be good if we could mark them... (they even ask us to mark them but they quikly remember we can't).
Even if the staff added you in CB, That doesn't mean that you can mark him always, I mean there is many reasons/abilities in CB maybe he added you only for chat. Adding this might get him annoyed even if he's your friend he might be busy but he doesn't want you to be removed from his CB. Why do you want to mark him actually? nothing important also if he wanted you to come he can ask you in /fmsg chat what is his current location. You know staffs are busy always, I hope you understand this point. Keep discussing I am voting nature.
When a staff adds a friend to CITBook, Then He would add him when he is sure that he is a good friend not an annoying one nor a troller. So by using common sense I won't go to annoy my friend (The Staff) since These actions are too childish, And Most of people won't waste their time in Marking their staff friends to annoy them through the time they are logged in. And the situation you are talking about is nearly not possible due to reasons I stated above. I appreciate your comment Anyway.