Generative Filmmaking & Production — Volume III: Persistent Generative Personas and Legacy Data Systems advances the Production 2.0 framework into the domain of entertainment metadata. Where Volume I documented compositing discipline and Volume II documented narrative architecture and safety intelligence, Volume III addresses what happens when a director-led generative workflow produces recurring non-human cast members that legacy relational databases (IMDb, MUBI) were never designed to hold. Using the Aevara cinematic universe as an active stress-test case study, this paper introduces the Persistent Generative Persona (PGP) / Persistent Generative Actor (PGA) framework — the argument that a locked visual blueprint (Commander Alpha) or a Locked Apparel Specification (the CEO's navy suit) can function as a valid, recurring database key across multiple independent artifacts. Frameworks documented: the Ontological Crisis of relational metadata, the Human Anonymity Inversion, the On-Screen Credit Primacy Protocol, the (Self) Attribute Loophole, the On-Screen Graphic Matching Protocol (OSGMP), the Human Audit Defense Matrix, and the Gilded Ledger transmedia-integration protocol. Produced on consumer-tier tools as part of the open Production 2.0 research series. Free distribution.