If a user is given "Edit" rights to shared content it is possible for that person to edit or delete content that was shared with them. Since these changes propagate to versions of the content (those of the content owner as well as all others with who it has been shared), there should be a way to notify the content owner of the an edit or deletion. For deletions in particular there probably be a workflow that requires content owner approval before the deletion takes place or an easy-ish way for the content owner to restore that deleted content.
