The LHR-EZE flight stops at GRU on the way but it's the same flight number. It's the same for EZE-LHR on the dates I've looked at. Does it only count as a transfer if it's a different flight number? When I was typing out that post I didn't have GRU there then I added it before I posted it since I had seen that there is a stop there on the dates I've looked at LHR-EZE and EZE-LHR flights. I can see now that I shouldn't have included it.