post
https://apibeta.familysearch.org/platform/tree/child-and-parents-relationships//source-references
Create a source reference attached to a child and parents relationship.
201The creation of the source reference was successful. Expect a location header specifying the link to the created source reference.
400If the request was unable to be understood by the application.
404The specified person has been moved, deleted, or otherwise not found.
429The request was throttled.