I started booking a flight FRA-CPT-FRA for myself (SEN) and my son (no status). I reserved 2 "more legroom" seats which showed no charge. It was only at the very end of the booking process that I got a message that an extra €25 per seat was being added for my son's seats.
I have booked many similar flights on LH, but this is the first time I have encountered this. Is this new?