public void ImportFromSupplementaryFile( string fileName, bool loadAsCustom )
Imports a collection of supplementary objects from the specified file.
If loadAsCustom is True, the data will be added to the custom DataSource; if no custom DataSource exists, an exception will be thrown. If loadAsCustom is False, the data will be added to the base DataSource.
If an object being imported has a GC code that matches an object already in the DataSource, it will be skipped.