According to this article,
http://travel.sina.com.cn/air/2009-0...91461169.shtml, Air Macau was making big losses in 2008 and called on its major shareholders including Air China for help.
Travelled to PEK from HKG last week, acft was A321, seemingly on damp-lease to Air China. It seems the arrangement has been in place since Aug(?) 2008.
Read what you will into the above.
FGP