Yep your right you can't have multiple JSON schemas. So we hacked the planet for ours thats generated at every build as part of pipeline. But what it does is download the schemastore online JSON schema and we merge that with ours. Elegant: NOPE. Does it work: Sure does https://github.com/umbraco/Umbraco-CMS/tree/v9/dev/src/JsonSchema I am sure @User would be happy if you got any ideas on how we could make it extensible or help package developers life's easier to generate their settings.