Oh well, I called up MPO today and finally asked them why my wife was given the complimentary Silver status.

It's nothing to do with me crossing the 180k again this year (previous rumours suggested complimentary spousal status for DM earning above 180k club miles, a very nasty and misleading rumour indeed!)

It's nothing to do with the new Amex card either.

As tedhl rightly suggested, it is because of revenue and premium class (full J) that earned her the Silver card. Her trips to London and Dubai costed ~HK$60k + $~HK$25K in air ticket alone. I guess if one is desperate enough one can spend that money on 10 HKG-LHR V class tixs and become a DM!