Well, you did call it. And they even managed to make it more questionable than what the Japanese had actually happen by making her look, sound, act, and actually be younger.
I am making a snide reference to the radio drama in which Maria had turned into an adult before they shacked up. Japanese Alucard gets to just barely beat the allegations.
As for Sonia, it was IGA who tossed her out of canon.
Presumably he didn't like the circular idea of Dracula being constantly beaten by his descendants, plus if anything the idea that Alucard would risk propagating his bloodline goes against his established character. Not to mention being a deadbeat father, which is something you absolutely can't pin on even Dracula himself.
