[beyond the sea]

Perhaps a kitchen worker at the reception hall and his girlfriend

I'm kidding..... but you're starting to sound like Howard Dean ( “You think the Republican National Committee could get this many people of color in a single room? Only if they had the hotel staff in here.”).

;-)

[Miss Marple]

PLEASE note I also noted that it could have been the girl (bridal store clerk) and her boyfriend. If they knew her as peripheral people in the wedding, they have to have been far enough in the background that she didn't recognize them.

Guy on MSNBC says that she either was watched and kidnapped or they saw her as a victim of opportunity.