Originally Posted by headinclouds

Be careful when booking an AA codeshare. There may be different availability on the codeshare vs the metal airline For me, no A class on JAL from TYO on the AA codeshare, while JAL metal did have seats. Also, the JV airlines may have better inventory amongst themselves. I thought that to use a codeshare flight the prior flight had to be the same airline as the marketing codeshare airline, AA -> AA codeshare, but not AA -> QR codeshare.