A novation by change of an obligee cannot be set up against a third person, unless it is done by a document with a certified fixed date.
Civil Act — Article 502 (Novation by change of obligee)
민법 제502조
For AI agents and developers — get this article as JSON, with the English and current Korean effective dates and an outdated-translation flag, from the korea-law API or as an MCP tool:
https://mcp.apify.com?tools=kr-data/korea-law