Before now, a comment posted on the comment of a Facebook user was notified as posting a document on the Facebook user's Wall. It was not natural.
Now, a comment to a comment of Facebook user would be notified via notification e-mail to the Facebook user!
Facebook user should allow SocialXE App. the 'e-mail' permission. You can change the 'e-mail' permission as you sign in again with your Facebook account. As you sign in, you might meet the permission modifying page. Website administrators should notice this permission change, and lead their members to re-sign in with their Facebook account.
This revision is applied on the SocialXE sandbox. It would be officially released.