post https://api.notion.com/v1/data_sources
Use this API to add an additional data source to an existing database. The properties follow the same structure as the initial schema passed to initial_data_source[properties] in the Create a database API, but can be managed independently of the properties of any sibling data sources.
A standard "table" view is created alongside the new data source. To customize database views, use the Notion app. Managing views is not currently supported in the API.