We'll create fresh WordPress site with Include Widget installed. You have 20 minutes to test the plugin after that site we'll be deleted.
Includes a file’s contents in the widget. Quick and dirty, all this does is use the PHP include function to include the specified file in the widget. There is NO checking done whatsoever on the file, so use it at your own risk. I wrote this because I couldn’t find a widget to do this ? plugins exist for using include in posts and pages, but not in widgets.