I don't mean to be too off-topic, but I think this is somewhat relevant.
So I am completing a CTS-TYO(stopover)-USA itinerary with my AS award and flying F from TYO-USA. Unfortunately, AS had no "saver" availability (E/T class) to connect/layover on AS metal from the US gateway to my final destination. So I have a separate AS positioning flight paid with cash on a separate PNR/ticket.
What is the chance and process of getting JL to interline checked bags according to JL F checked baggage allowance to allow my final positioning flight on a separate AS PNR/ticket?