It's often possible to find AA-operated flights with BA or IB flight numbers between the EU and the US, and they will count for tier qualification. I recently flew FCO-PHL-ORD-FCO on AA with BA flight numbers and those were counted by BAEC as three qualifying flights. The fare with BA or IB flight numbers booked on ba.com or iberia.com is occasionally even a bit cheaper than if it were booked on aa.com.