Thank you all for your very useful suggestions. About the MCT not being a problem, I am not so sure (at least from the ba.com's point of view). I tried booking the trip as a multi-city itinerary (LHR-GRU, EZE-GRU, GRU-LHR: the last two trips on the same plane) but I got a message saying that this is not possible as I need 120 mins MCT- I guess this refers to the EZE-GRU and GRU-LHR segments. So this means I would definitely need to book the EZE-GRU ticket as a separate PNR (at least on ba.com), if I make this trip.
Originally Posted by
nielsdc
In my experience you can only check bags through if the connections comply with the minimum connection times. As far as I know the computer is not smart enough to merge the 2 flights together, and so indeed your bags will go out of the plane in GRU, and will be loaded again with the other luggage from GRU.
In this case, it seems the MCT is less then the time spend on the ground in GRU, so it should be no problem.