I did not know islands were supposed to defect. In my latest game (agceep) I saw malta defecting to the Knights! I am NOT talking about some kind of event here, just a plain defection. At least, I did not see any evidence of an event firing. It was like this: The Ottos held malta. Rebels captured it => province defected to the Knights. Ironically, that triggered the event for the Knights to give up rhodes, so basically they just switched islands with each other...