Haven't been able to figure out how to do this on the BA site and searched other threads to no avail.

Trying to do something like ORD-SCL-EZE-ORD as a single booking. Is that a phone job? It would require flying both AA and LAN. I can book these as three one-way legs but I'm not keen on spending 12,500 miles for the SCL-EZE leg, which is a 2-hour flight. Have found lots of availability for the individual legs in May/June when I'm looking to travel, so that's not the issue.

If I just wanted to book an open-jaw ORD-SCL, then EZE-ORD, I'd have to do that by phone, right?