Update: I just tried booking and buying a similar itinerary to see what would happen: NRT LAX DFW JFK LHR AMS HKG NRT but this time departing from NRT on a JAL flight to LAX rather than an AA flight. I was able to process this but then see at the bottom of my confirmation email "For changes to your booking please contact your ticketing carrier. You will receive your e-ticket from American Airlines".

I login to AA with the record locator number and see the same" contact reservations" . So, Japan Airlines uses AA to issue tickets. I answered half the above question. Does anyone know about who issues tickets for a BA flight out of NRT.

I was comfortable doing this as if the ticket was issued, I could cancel the above ticket; in this case I will just cancel this booking and take my first booking repriced 40% more.