No, their full family name is C D. If you must abbreviate it, the correct address would be Sr C, not Sr D. There is no way that entering D in a "last name" fiel

No, their full family name is C D. If you must abbreviate it, the correct address would be Sr C, not Sr D. There is no way that entering D in a "last name" field would be correct unless you're aiming for passive aggressive obstinacy. To take a famous example: the full name of Rafael Nadal is Rafael Nadal Parera: one given name and two surnames, with the first surname taking precedence.