My fiance's parents don't speak a word of English and just took a flight from Taipei to San Francisco. We have not heard from them, but I think I've found a way to determine whether or not they boarded their connecting plane to MCI.

I used a Regional Premiere Upgrade to get them in First Class from SFO to MCI. The plane has taken off and the upgrade list still shows them in their respective First Class seats. If they didn't board the plane, wouldn't that have changed to some other person who got upgraded to their seats?