That's questionable and doesn't address what was in the question!
Where does it say that it is a drow tradition, rather than a Sharg tradition? Where does it say that the Sharen Vals followed that tradition? Where does it say that Snad raised Sarv? Please provide the links that prove what you are claiming.
As I just asked, why would that apply to the Sharen Vals when they have plenty of servants to do it. Well, servants and slaves, really. That's why I doubt they did it the same way as the Shargs did. I'll also note that the Shargs don't have protector twins like the Sharen do, so obviously the different clans can do things differently.