A FlyerTalk Posting Legend
Join Date: Sep 2009
Location: Minneapolis: DL DM charter 2.3MM
Programs: A3*Gold, SPG Plat, HyattDiamond, MarriottPP, LHW exAccess, ICI, Raffles Amb, NW PE MM, TWA Gold MM
Posts: 100,369
IIRC TK and maybe some of the ME3 carriers started doing these companion fares several years ago. In particular, I remember a Valentine's Day sale on long haul business class tickets, but it might have been one of the major European carriers such as BA.
I'd be afraid that if you try to split the PNR and cancel one ticket, this could be discovered on the day of travel (or even later) and you'd be charged a full unrestricted walk up fare for one person.
OTOH, the fare rules say "must be accompanied by...." without mention of being on the same fare or on the same PNR, so maybe the companion can technically be using an award ticket as long as they travel together on all segments in the same cabin (so no OPUPs for one person only, if OPUPs are possible on the flights--maybe there's a partner operated segment with a FC cabin?).