I have BA First flights booked with Asia Miles with the following itinerary GRU-LHR-SYD. The GRU-LHR flight was supposed to be this year but it has been cancelled by BA and has dropped off the itinerary. The LHR-SYD flight is next year and remains in MMB. Can I still fly the remaining LHR-SYD portion and what would be the implications for taxes and fees? Reducing taxes and fees was a big driver for making GRU the starting point as they would normally be much higher if the itinerary started in LHR.