I wonder why we can’t have a hyphenated last name (the one we put in in Book 1 + magical lineage surname) in Book 3. Most of my PCs would want to do that instead of completely replace their names. The Anderson magician and Castella hunter would keep their names, the Anderson nephilim would be an Anderson. The Castella kitsune might hyphenate Anderson and her given last name (to honor Aunt Dru) because after learning about dear Roxy, she hates and pities the woman, and wonders about Roxy’s mental health.
Plus, in the Keeperverse, there’s precedent for powerful people having hyphenated names: Patil-Conti, for example.