A BA phone rep told me that every flight has to be a BA codeshare (i.e. have a BA flight number). That gets tricky because I can't find BA numbers for AS LAX-MFR or AA MFR-PHX.
Am I likely to have better luck with a different BA agent?
Will I have better luck with AA flight numbers vs. AS numbers?
Is there a trick to finding weird codeshare flight numbers?