I've done 3 DONEx itineraries in the past, all booked through the AA desk. I'm planning another one and this time want to credit some segments to AS, which earns more on BA numbered flights than AA ones. Itinerary is starting off as OSL-LHR-JFK and the AA desk wants to issue LHR-JFK as its own codeshare. So, should I book through BA to achieve this and if so, do they have a competent RTW desk and how do I reach one?