Calling on all the experts...Before seaching and buying a One world RTW ticket the following is my itinerary (wish listed)

SYD/YVR;YVR/CPH;CPH/ROM;ROM/SYD

Now the problem is Cph to Rome.Can I take a BA flight from Cph via Lon to Rome.That is the problem as there are no One world airlines that fly Cph to Rome

Thanks for any ideas

A variance could be Yvr/Ams;Ams/Cph then onto Rom etc