Many thanks for explanation. Makes sense that JetBlue may no longer have a codehare flight No. for a flight wet leased from Oman Air, but still beyond me why JetBlue can't rebook to the QR prime flight No.for tickets already issued (surely, the DOH-EBB flight has a QR flight No despite being operated by Oman Air). Would DOT really allow airlines to cancel and leave pax hung out to dry in this situation? (when the flight is operated but issuing carrier is no longer able/allowed to book it under its codeshare flight No.)