For any given simple or complex object, you can manage supplemental or variant versions of files using the "Files" tab.  

As an example, you've accessioned a digital photograph collection, and have two variant file versions: high-resolution TIFF files, and raw DNG files.  You'd like to privilege the TIFF file as the primary file (in the "Main Content File" section), so it will be utilized to generate a service/display image once published in Calisphere.  But you'd like to hang onto the copy of the DNG file, as a variant version.

You can store one or more variant files in the "File" tab in Nuxeo.  Click on the tab, and select and upload the files.