Adding certain apps to the Nokia Lumia 920 Notification + Action hub??

[Unregistered]

Hi, so a couple days ago under the Notifications + Action hub on my 920 I had two app in there it was a free texting app and it was the Facebook messenger app, and I would get notifications for them but I noticed today that I wasn't getting notifications for the two apps, and I checked the hub and I noticed they were gone, is there any way to add certain apps to the Hub or no? Thank you!