Originally Posted by
rogodwin
Next spring I plan to do a DONE5 starting from LHR to SYD and I understand there are fee, etc. differences between the airlines that issues the tickets. I can either fly BA or QF for the first flight.
Is there a cost advantage to buy the ticket on either QF or BA?
Can I buy the ticket on AA although the first flight is not on AA?
Thanks in advance.

There is a huge cost advantage to buy the ticket through AA because the fuel fines are much lower or not there at all. This can be a $1000 difference compared to BA or QF. Who has the first segment is irrelevant. In theory, any OW airline can ticket even when they don't have a single segment.
In reality AA likes to see some AA segments in there. If you are really unlucky, AA might insist on an AA overwater segment (can be a codeshare). But normally there shouldn't be any problem when ticketing through AA.
Their RTW desk is very knowledgeable and good to deal with.
By the way, you can fly a lot more airlines for the first flight. CX comes to mind but also RJ, JL or AY.