Often AA.com will provide options for a flight both AA coded and non-AA coded when searching using AA plus oneworld. In my experience sometimes the flights (or airline coding) you want don't always show so playing around with search by schedule, price, AA+oneworld and all airlines can help. Sometimes forcing a routing with a multicity search (with all the permutations above) gets you what you are looking for. It's funny that for some searches, I have to go to all airlines to find itineraries that don't show up on AA+oneworld even though they only use oneworld airlines!