I have the family tree of Gino, Ian, and Louie in my head right now
Ian, and Louie are the children of Vlad and Rosalie.
Gino is the son of Gambino and Rosalie.
The Von Helson sisters are the daughters of Vlad (not sure who the momma is, manga doesn't say)
So, Ian, Louie and the Von Helson sisters are half brothers/ sisters to Gino and visa-versa.
~Now when you throw in this hypothetical match of Momma Kuro and Vlad~
Luca and Cordell are the children of Poppa Kuro and Momma Kuro
we don't exactly know who the Z- chap is (i can't spell his name) so i'm just going to go with; he is the son of Vlad and Momma Kuro angle.
So if Z-chap does turn out to be the son of Vlad and Momma Kuro, that would mean that;
Luca and Cordelle would be half brothers to Z-chap.
That would also mean that since Vlad would be Z-chap's father, Z-chap would also be half brother to; Ian, Louie, the Von Helson sisters, and Gino.
Do i have all that right? It's rather late here...
He wouldn't have any relation to Gino, just Louie, Ian, Luca, Cordell and the twins.
Ian and Louie are Vlad and Rosalie's children.
Gino is Gambino and Rosalie's child.
The Von Helson sisters are Vlad and an unknown human woman's children.
Luca and Cordell have the same mother, but it is not certain if they have the same father.
It is not confirmed that the high-born Kuro husband is the father of Luca and/or Cordell.
Luca and Cordell could be the children of anyone who was with their mother.
Many of the other characters' lineages are unknown.
Zhivago and the new Countess lady are vampires with unknown lineages.
The only major characters we know for sure have/have had vampire blood in them are Vlad, Zhivago, Ian, Louie, the new Countess lady, and the Von Helson sisters.
After looking at this, it becomes clear that Vlad could be the father of anyone with vampire blood in the Gaia world. They haven't told us of any other canon vampire sires.
So my guess (depending on whether or not what is being said in this thread becomes true) is that Vlad is the father of all major character vampires. Therefore Zhivago, Ian, Louie, the new Countess lady, and the Von Helson sisters are all either siblings or half siblings. In the case that Vlad is the servant and Cordell's father, then Cordell would be half siblings with Zhivago, Ian, Louie, the new Countess lady, and the Von Helson sisters.