Hello and welcome to what will be a general archive of who is whom.
I will make a separate one for each Family, and as of right now, each family is assigned one number, and its subsequent family units will add onto that number.
The original Rostand Family's number is 1, and that of the family unit of their firstborn will be 1.1, their second child's will be 1.2, and once 1.1 have a family on their own, they'll be 1.1.1, and so ad infinitum.
Feel free to ask any questions you may have, I understand just how complicated this seems to be.
If the children of 1.1.1 (in example) were to lost the surname Rostand in favour of that of their spouse, their descendency will not be recorded further, unless they have married into an affiliated family or a branch one, which are those of travelers with no other relatives.
A number will be then tackled to the family name; that way the Wilson Family is assigned the number 4.
Relating specifically to the Wilson Family is also the fact that it existed before its alliance with the Rostand - therefore, though we'll take the original family as the one that Dana created with her husband, we'll also take into account, even if slightly, Zidane's aunt and uncle. As we rise through the Wilson's family tree, the system will be similar to this:
Zidane & Dana are 4.
Rafita & Valeria, Zidane's parents, are 4-1.
Byron, Rafita's younger brother, and his family will fall under 4-1.1
Orsola, Rafita's younger sister would be 4-1.2