Just wanted to share some very positive feedback. Had a one-way JAL flight NRT-PEK before connecting on to a separate ticketed S7 service PEK-OVB-TBS.

I had difficulty completing online check in for the S7 flights however without any questions JAL was able to print boarding passes for all sectors and check my luggage through to the final destination. Due to entry requirements transferring in China and Russia is never fun and so having all boarding passes in hand, and luggage checked through, was hugely reassuring.

I just wish that all oneworld airlines would offer such a service. (E.g., Unfortunately BA would not have done this).