Thanks. I had some success today. Rang the premium desk and the operator thought my booking was a classic. Then, just like yesterday, suggested I should book a separate domestic leg if I wanted to travel on a separate day (!!). Asked a supervisor who conceded it was an ASA and gave the add-on flight details.
So I changed a SYD-xMEL-LHR FASA to add a MEL-SYD JASA two months prior for ~$165.
Also had the above LHR-xMEL-SYD FASA changed to add a SYD-xMEL-ADL JASA a few months later for ~$275. So not as cheap as others have quoted, but they are stopovers and slightly cheaper than booking the Y equivalent fares separately. These were originally JASAs that were "upgraded" or "up fared" to FASAs so I don't know if that factors in to the price change. If only I knew about adding those domestic sectors beforehand - "wasted" two FASAs that have already been taken!!!
The e-tickets haven't arrived in my inbox yet, but from what I gather they were kinda complicated to do - over 30 mins in call time. So until the ticket arrives I guess there is some uncertainty, but the bookings have been updated in MMB and I have selected seats and whatnot (not that it makes a difference). I recently had an F classic award take over a week to ticket... but two domestic bookings made today ticketed within 15 mins.