DH and I plan to go to Prague later in the year with my brother and his fiancée. DB refuses to fly and I'll be very pg in any case, so we're going to make a road trip of it and then my parents are going to fly out with DTs (6) and meet us there. Having different surnames to the DCs, are they liable to run into difficulties proving that they're not abducting them or something? If so, is there any way round this?