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: 102,617
You cannot add a person to your PNR. You can only split a PNR or link different PNRs.
You can request a free companion upgrade for your wife. You might be able to use one of your RUCs for her upgrade. IIRC officially she must be on your PNR (check the T&C on your RUC) but unofficially people seem to have done this successfully by calling DL.