We're using the Feed Wordpress (Syndication) plugin to ingest external feeds resulting in posts published in WordPress.

The plugin pulls the 'source' URL from the feed. We can display the source URL fine against the post on home and post page, but if the feed owner did not include a source URL, it does not exist.

We want to be able to pull the source URL from the feed into a custom field, so that the URL populates the custom field. If the feed has no source URL, then the editor/contributor can access the post editor and add one.

Is it possible to pull the source URL from Feed WordPress (or any other plugin that uses feeds) and populate a custom field with the URL if exists. If not, then the user can add one?