There is a thread in the BA Forum Dashboard on Theoretical Seating. It's quite a detailed thread, and TS applies 3 days from departure when the booking goes to FLY, but yes one of things it does is keep people in the same reservation together. Maybe not in the way you would want, and sometimes it is nearly impossible to do. He - as the Bronze cardholder, should log in at exactly 7 days to departure, get the best pair you can, then keep an eye on it as you near departure. At OLCI have a further go, but don't print your boarding passes unless you are completely happy with the pair of seats involved. Incidentally the Theoretical in TS is that if your seating preferences were window seat, theoretically this is what the module would choose for you.