Originally Posted by CPH-Flyer

Basically, IB and BA are responsible for seat selections, that is the agreement they have with JAL. I know their call centres like to say "call JAL" but I guess that is a lack of training on their side.

But the challenges with seat selection on codeshare is a reason why I try to avoid codeshare on the long haul bits. I recently did a BA code on AA LHR LAX and back though, and while seat selection was a bit wonky, BA eventually got me there.