News is a shared collection of content and we can't add customer sources. However, you can ingest custom sources in Watson Discovery service.
Alternatively, you can check if a source is included in AlchemyData News service with this query, where YOUR_API_KEY is your AlchemyAPI key and wikipedia is the domain of the source you want to check (omitting any subdomains, top-level domain names, or second-level domain names):
News is a shared collection of content and we can't add customer sources. However, you can ingest custom sources in Watson Discovery service.
Alternatively, you can check if a source is included in AlchemyData News service with this query, where YOUR_API_KEY is your AlchemyAPI key and wikipedia is the domain of the source you want to check (omitting any subdomains, top-level domain names, or second-level domain names):
AlchemyData News API reference