I must not be making myself clear. It is only row 16 or 17 (depending on configuration) that can not be pre-booked by anyone. I have tried, 1k's I know have tried. United has consistently said no to that bulkhead only. It is the bulkhead that basinets can be attached to so they will NOT pre-book it and save it for families with babies. You can get it at the gate if they know no babies are boarding. If you have been able to pre-book this row consider yourself very lucky. United has been pretty adament about it.