I got a theory about The Creation of The Vampire Queens that they are Dhampir-Witches (Half-Vampire Half-Human) like many former witches like Succubus and Warlocks etc are former witches and they still side from being former witches meaning they had the basic powers of Spell casting, Potion making and Scrying
when they become vampires they gain the additional powers. If the sisters turned into half-vampires, the book would be turned too. The book changes as the sisters change. And then they would have been to powerful for The Current Vampire Queen to control The newly turned Charmed Vampire Queens.