I'm a bronze executive club member through BA, fly to europe a couple times a year. I'm trying to gain silver by november. I'm looking to book first class on an American Airlines flight to Aruba. Do I need to book it through BA to get tier points, or do I book through AA and add my executive club number there? BA keeps saying they can't find the flight, and I want to make sure it counts towards my EC account not my AAdvantage account.