After my last reply I called the Diamond Line again they reassured me that my Mlife nights count and with my most recent booking they will be extending full Diamond status until Feb. 2015. Because it has become a case by case basis I would recommend having more than just M-Life stays during your challenge. By the time the Challenge period ends I will have 9 M-Life nights and 9 "Hyatt" property nights along with my emails and conversations with HGP. If your Challenge looks similar to mine I can't imagine them not making an "exception" for you (even though the T&C isn't clear)