In Reply To #4
They would be Belmont if they were decendents of Sypha and Trevor, rather, they would be half and half, a nice, strong cup of Beladmont.
However, if Sypha were to have a brother or something, which is more than possible, she could have tracked him down, and taught him/her/it magic/informed them of their new family and destiny, and thus, the Belnades were formed