I was hoping to book LAX--GRU--EZE using SkyMiles (Option 1). I am not sure if it is possible to do the second part (GRU--EZE) with SkyMiles, but it looks like some of the Argentinian carriers have a codeshare with Korean (if that matters). If I can't book the second part using miles, I was planning to use miles for LAX--GRU and then just purchase GRU--EZE through the Argentinian carrier (Option 2).

Does anyone know if, under either Option 1 or Option 2, I will have to retrieve my luggage and/or go through immigration in Sao Paolo? I would of course much prefer to be able to check my luggage all the way through and not have to go through immigration.

Thanks in advance.