You would have to buy an extra segment in D and use it wisely (looks like 1360 points are highest possible for 3 continents and this is only with careful routing). Easily reached in F though. QF and CX are both fine for their RTW desks, BA is pathetic (they contract the work out in NA), AA is the best but no need to use them. Once the ticket is issued any Oneworld airline can make changes and re-issue (even if they are not flying a segment on the ticket, though they are not keen to do this work). BA is the best for reissuing, particularly for segments flown on BA (fast, fair, competent, unlike their reservations on the 800 number).
AA is the opposite (most AA ticket counters go into shock at seeing a RTW ticket and have trouble pulling the coupon, much less rewriting it, while the 800 number is *superb*).
QF is stingy with op-upgrades, don't expect too much (even as Plat). Award availability is tough on QF, partly high demand and partly policy. Much better if you are QF Plat but it can still be tough (much better for single seats within 2 weeks of departure date, and close to a sure thing within 48 hours of departure, but some people aren't so flexible in booking awards). Because of this there are often empty F seats on high-demand QF routes (and hundreds of denied requests for those seats); it does make it easy to get a paid F seat on QF, I have often changed flights less than a day before and the seat is available (no status required, just money). AA by contrast is sold out in 3-class trans-cons (filled with upgrades and awards) making last-minute paid for tickets impossible to get on those flights (at least not in P). At first I thought the QF policy was unfair, but now I like it. The big benefit of Plat on QF is irregular operation (rather important if you can't afford to be stranded for a day).