I don't understand what you mean by "using DSOfile for Office AddIn"?
You'd need to work with each application's event that triggers when a Save command is called. In Word, for example, that would be DocumentBeforeSave. Excel and PowerPoint each have their own event. When the event is triggered, check for the entry. If
it's not present, cancel the event and show the user a message.
Cindy Meister, VSTO/Word MVP,
my blog