Well, it always seemed to me that Abdullah has a soft spot for his youngest half-brother Prince Hashim. But Princess Raiyah also attended, that's half of Noor's children there.
Perhaps Princess Iman was making a point by not attending, but we don't know what goes on behind closed doors, maybe Hamzah doesn't want his full siblings to be blacklisted.
I know that she and her husband attended too; I didn't mention her because in Jordan woman can't inherit the Throne.