Moderator: United Airlines
Join Date: Jun 2007
Location: SFO
Programs: UA Plat 1.997MM, Hyatt Discoverist, Marriott Plat/LT Gold, Hilton Silver, IHG Plat
Posts: 66,860
You will need to book separate tickets. Every one on a PNR must be booked using the same fare class, so no mixing of award and paid tickets on a single PNR.
This is true for online or in person TA bookings.