I want to book and upgrade a WT+ ticket from the USA. Now, I can do this online if all segments are on BA. But my trip is starting in a non-BA city, and it won't let me book and upgrade from a non-BA city. I don't know if this is because there is no availability on the non-BA operated flight to the BA gateway city (there is availability on the BA flights), or if you just can't book and upgrade when the itinerary contains non-BA operated flights on ba.com

My question: If I book and purchase the WT+ flight online (originating in the non-BA city), can I call and upgrade the BA portions to CW and CE (of course assuming there is still availability).? The route is TUL-ORD-FCO, with TUL-ORD operated by AA but with a BA flight number. I am assuming MFU doesn't get you first on AA, but I don't care about that at all. I just want to make sure that I can still upgrade the ORD-LHR-FCO (which is currently available for upgrading).

I consulted the sticky but couldn't find a specific answer. Thanks much.