Btw: Don't expect, that you can manage that kind of booking like any EY booking on the EY website.

For me it's a normal procedure after booking a topbonus (AB stock) award, all legs operated by EY. topbonus/AB works with Amadeus, but I can get the EY code from the topbonus hotline or from CMT. But even with the EY code, most of the time I can't change i. e. the seating, because the booking werent made by EY.