Can you make a screen capture, or diagram showing exactly what you want to do? I just can't picture it.
If what you want to do is place it directly under the Open command in the File menu it would not be easy. The only slight possibility I can think of would be to create custom ribbon XML code to modify the "Backstage Pane". I
How do I change Backstage(File) view in Excel 2010
Customize the Office User Interface in Office 2010
http://technet.microsoft.com/en-us/library/ff468686.aspx
Updated: September 9, 2010
This article lists resources that will help you customize the Microsoft Office Fluent user interface (UI) in Microsoft Office 2010 applications.
Microsoft introduced the ribbon extensibility model in the 2007 Microsoft Office system as part of the Office Fluent UI. This was a new way to customize the user interface and create custom tabs and groups that
were specific to users needs. Office 2010 extends the span of the UI extensibility platform by providing support for customization of the new Microsoft Office Backstage view.
Customize the Backstage view
In Office 2010, the Microsoft Office button is replaced by the
File tab. The File tab brings you to the Backstage view. The Backstage view is customizable and lets organizations customize the UI to suit their needs.
For information about how to use and customize the Backstage view, see the following resources:
Introduction to the Office 2010 Backstage View for Developers (http://go.microsoft.com/fwlink/?LinkId=182189
http://msdn.microsoft.com/en-us/library/ee691833%28v=office.14%29.aspx
Customizing the Office 2010 Backstage View for Developers (http://go.microsoft.com/fwlink/?LinkId=184245
)
Change the Ribbon in Excel 2007 or Excel 2010
http://www.rondebruin.nl/ribbon.htm
Ron de Bruin (last updated 6-Oct-2010
<snip >
More RibbonX examples
You can download 8 Excel files here with basic RibbonX examples for Excel 2007 and Excel 2010.
Download Example Excel files Last Updated : 27-June-2010
- Add custom group in built-in tab.xlsm
- Add menu and buttons to Backstage or Office Button.xlsm
</snip>
I haven't seen any documentation about customizing the 2013 backstage.