Join Date: Oct 2006
Location: London, UK
Programs: BA Gold, VS Silver, SQ Silver, IHG Plat Amb, Hilton Gold, Marriott Plat, Accor Silver, Radisson Prem
Posts: 16,873
No, all pax on the same booking must be travelling in the same class. If you want to MFU, you must MFU all pax on the booking.
Your best bet is to do two separate bookings.