I also really like
Yevgeniya on a girl. WAAAAAAAAAAY cooler than
Eugene /
Eugenia.
I do like it with
Vadim, but I'll give some more suggestions:
Yevgeniy RadomirYevgeniy AleksandrYevgeniy NikolaiYevgeniy LeonidYevgeniy SamuilYevgeniy AnastasYevgeniy Anisim -- I really like this one
Yevgeniy KazimirYevgeniy VeniaminYevgeniy MaksimYevgeniy MaksimilianYevgeniy Radoslav
The sibset is really awesome, as far as Russian names go. I'm not a big fan of
Vladislav or Berislav; there are other -slav names that I prefer.
Milan feels awkward with brother
Miroslav, sort of like a random adoptee in the family. I'd use
Borislav Milan instead of your current combo. Go Russian/Slavic names!