If in any case you cannot find a Data Mapping & Risk record that you can map to a specific data source, then you can create a new record. Click the field to the right of the source, and then click Create New System.
A Create System modal appears. At minimum, you must complete the System Name, Owned By, and Hosting Location(s) fields.
After clicking Save, the new Data Mapping & Risk record is automatically mapped to the data source.