I'm looking at booking BRU-LAX return in W and using SWU's to upgrade. Availability shows R9 BRU-ORD and ORD-BRU and R0 ORD-LAX and LAX-ORD. Can I book the ticket and use SWU's to instantly upgrade the transatlantic, and get waitlisted on the transcont, or will I not be able to upgrade until the entire itinerary clears?