Surely If EI flights are from bfs they will want to fly from bfs themselves to keep it all under one roof. ie if pax miss a flight with Ei they can get on the next BA flight from BFS etc or if a flight arrives late into heathrow they can get on the next code sharing flight, in my opinion and knowledge it is too expensive to split over 2 airports. Also if all put under 1 roof at BFS that is potentially an extra 400,000 pax however I think if this did happen BFS would need a new airbridge