Excellent, many thanks. In fact I resorted to the very old fashioned method of phoning Cathay! Ticketing can't help but they can get someone to call you who can tell you the fare (around USD 10 as seems reasonable these days). My next step will be to call ticketing with the entire itinerary and ask them to have the RTW team check it and give me a call back. I have to do that because using the Oneworld itinerary planner told me that I had too many segments after I reached 12 and wouldn't let me book it online, I guess still some bugs. But Cathay called me back very quickly so it may not actually be too difficult to book it with them.