I know this has been discussed but it's hard to search for this info.

I may buy a CO-coded itinerary, outbound operated wholly by CO, return operated wholly by UA. The return is EZE-IAD-LHR. All booked in W class (Reason: because there are CO flights, I can't get .bomb to offer me W class on the return, only S class. I know I may call, but this is a complex itin and I need the EQMs from booking online. Continental.com allows searching for specific fare classes but then only returns CO-coded flights).

- I know one can only upgrade codeshares with SWUs on the day of flight. I guess there is still no exception if the codeshare is with CO?

- How confident can I be that CO W class will be mapped to UA W class, so that I will be allowed to apply the SWU on day of flight?

- Assuming all goes well, can the IAD-LHR upgrade be confirmed when I check-in @ EZE?

- Any experience with these things in EZE? I'm generally not very trustful of outstations when it comes to unusual requests.

TIA ^