Join Date: May 2004
Location: formerly Gold now Diamond, formerly MSY, now LAX, formerly NW, now DL
Programs: Hyatt Plat, Hilton Gold, SPG Gold, Delta Diamond/1MM
Posts: 4,635
No, technically you can't get the free bags for others outside of the PNR you are booked in. Others with a different PNR (reservation) can be linked to yours (in case say there is issues with flight) but it doesn't get you the free bags. However, a nice check in agent maybe able to get that done. Also you should check as many under your name as suggested above.
For future complex bookings, I usually call the agents and have them do it. I suspect they have a way to get you all under one PNR