Googling to find the English equivalent name of Yakov we find the English is Jacob or James.
Yakov (alternative spellings: Jakov or Iakov, Cyrillic: Яков) is a Russian or Hebrew variant of the given names Jacob and James.
So James de Smirnoff could be represented as Yakov, Jakov or Iakov.
Therefore, referring back to this profile, we know elsewhere that James had 3 brothers, being:
Jean de Smirnoff (Ivan)
Stepan
Ioann (not Yakov shown here in this profile because he (Jakov) is James)