Although my particular case involves the GH HK, this could apply anywhere.

I currently have a 3 night FFN reservation for the Grand Hyatt HK. Although I'm Diamond, there is always a question on getting upgraded to a Club room. If I change the first night to a Club King using points, would there be a possibility that they would move me to a lesser room for the additional 2 nights?

P.S. Currently all three nights are available for a Club room with points.