Id be suing a combo of SWU and Miles thus I stopped here.
Here's the scenario with question:
Booking thru AA.com on BA metal all legs.
Routing is JFK to FCO via LHR.
When searching AA award ticket as JFK to LHR only, the saver price of 57.5 is available for my target first leg.
Can I book the full ticket: JFK to FCO (thru LHR) via AA in Economy and then upgrade the JFK/LHR leg using SWUs and Miles?