Basically you want a document management system, is that correct?
There is a requirement to explore this functionality in Workflow Manager but it will not be in the 10.1 release.
For now, using linked attachments with a UNC path is the way to go. If you have a document management system (SharePoint) in place, you can use a combination of "Linked Attachments" and the check out/check in capability that you get with MS documents to keep track of these changes.
Hope this helps!