Board Thread:Naruto Discussions/@comment-33276259-20171006221012/@comment-25122992-20171029135442

Plus, Oonoki was never called "Oonoki Kamizuru", just meant to be a possible member of the clan by heritage (and even direct members don't always have the clan name as their family name, as witnessed by Nagato or Kimimaro never using "Uzumaki" or "Kaguya" family name), while Yagura was called "Yagura Karatachi" right away, even before we learned that he's Kagura's grandfather. So, the cases of Oonoki and Yagura aren't actually comparable at all.