Absolutely. Work out a Oneworld route that works for you then ask for the specific rebook to those flights when calling up. Keep within the joint venture airlines/routes so AA/BA/AY/IB are all up for grabs. So many variations on what can be done here, you don't need to keep to the original routing that you paid for. AY EDI-HEL or BA/AY EDI-LON-HEL then AY to the US East Coast/Midwest followed by AA to MKE would be a permitted rerouting. Use this as your opportunity to maximize your tier point collection (backtracks to the West Coast or QR via Doha aren't permitted reroutes... just to save you time and face).