            "This is where my research turned out to be quite fruitful. You see," Ollivander said, readjusting his apron with a sharp tug, "when a witch marries a wizard, her name vanishes from its prior location in the Book. After the official marriage binding ceremony, her name instead appears on her husband’s page. If a Pureblood witch were to marry a Muggle-born wizard, her name then appears among the other Muggle-borns, as do her children. It is why that particular pairing is so rare in our society," Ollivander continued with a somber frown. "If this witch performed an illegal marriage ceremony—if she nor her husband alerted the Ministry to the name change—the witch becomes virtually untraceable. She disappears into the back pages of the book, lost among the sea of undocumented Muggle-borns. Her underage magic pings the Book’s alarm, but it is as if she is a yet unregistered child. No name to speak of, until a Ministry worker or Hogwarts professor tracks her down. And if she had this potion," he said, tapping the rounded glass, "she would be impossible to find."