You could check mark the 'unused files in project folders' box in the 'Export Package' options, but then the excel sheet would need to be stored in one of the five project folders (Audio, Video, Models, Images, Fonts). But it's likely easier and more clear to just send the excel sheet separately from the xpp file.
Don't forget you'll also need to send your end users the Datalinq server settings, so their XPression engines will connect to their local Datalinq server and be pointed to the same data sources. In the Datalinq server go 'File > Save Configuration'. This will create a .dsc file that your clients can load by going 'File > Load Configuration'.
XPression Project Server can be purchased as part of the XPression workflow and is a huge help for distributing XPression packages and their accompanying assets to remote clients.
#XPression