Allowing Document Custody Between Projects

Often times we find ourselves referencing a single document/file between projects. If a user makes an update to that single document/file within the single project, other users on other projects are not made aware.

There should be a way to check a box indicating that "this document/file is shared with projects/tasks/issues" and a dropdown to select those it's associated with.

That way, when a user updates the document/file, all projects contain the updated document/file.