I am having difficulty understanding the exact relationship between JAL, oneworld and Japan Air Commuter flights (specifically looking at either FUK-KUM or ITM-KUM) which are operated by Japan Air Commuter to the island of Yakushima. Some sources suggest that JAC flights are part of oneworld and others do not. On JAL's site there seems to be award availability on a domestic flight, but if you select "international flight" anything operated by JAC seems to not show up. As a follow-up can JAC flights be booked with oneworld partners such as AA? KUM airport doesn't even show up in a BA or AS award search. Furthermore, if a segment on JAC is booked with JAL miles as a domestic flight and the international segment is booked with a oneworld partner (i.e. AA) will the reservations be able to be "merged" in terms of baggage going through?

Thanks in advance for any help.