I have an existing avios booking for PEK-HND in J with JAL a few months from now. It is due to land at 12:55 and there is avios availability showing on HND-CTS leaving at 20:40. It wasn't possible to book PEK-HND-CTS all as one originally, the individual flights were available but I think ba.com has issues...

If I call up can I add the HND-CTS to my existing booking? Or would I need to start again, which I wouldn't want to do as I think I would have to release the PEK-HND flights and hope the availability comes back.

If I can't add the flights, do you think that is a safe enough margin for a separate booking (12:55 arrival in HND for a 20:40 departure to CTS).

Finally ba.com is only showing Y and J, but jal are selling Y, J and F. Is there some magic time at which F might become available for avois? Are they reserved for JAL elites, or do I need to call because ba.com...