I was travelling on an oversold CA 983 flight from PEK-LAX yesterday with my father and we both received op-ups from Y to J at the gate. Needless to say it was an awesome boxing day surprise. In any case, neither of us were a part of Air China's FF program. However, my father is an OZ Diamond (*Gold) and I myself am US Silver Preferred. I assume that CA FF Preferred members got the first op-ups, but then I get lost.
My question is: how does the op-up structure work for Star Alliance customers? I am thinking it goes from the carrier's preferred members (in my case, Air China's preferred members) and then it trickles straight down to other Star Alliance preferred members, therefore passing regular CA FF members. Or is it possible that all CA FF members got op-ups before my father and I, and we were just extremely lucky?