User blog comment:Kaido King of the Beasts/Chapter 838: The Man Behind the Carbs/@comment-178.245.153.82-20160901133915/@comment-26803131-20160901153405

Yes like 12th said while Sanji cannot change his blood I feel as if he has officially renounced his family ties, which would include the name, title of prince, kingdom, etc. Makes you wonder why he kept the name Sanji at all. Gonna assume more flashbacks coming in time.