As for her history... hrm. Its certainly interesting, though a bit more over-the-top than most islanders. Though it definately had potential is played well. Does SHE know she's not a "real" princess, or will she have to face the islanders not believing her?
How she GOT to the island needs a bit of work, though. For example, Moreau would never, ever talk to her father directly. Moreau own's a whole company called Feral Labs, which is the "legit" side of his business. Now, someone from Feral Labs might have very well been in negotiation with her father.
Like with Ty-chans little girl, they probably would have offered to do a "risky surgery" for a large sum of money, and an insurance clause. Iona would have been shipped off to the island, and then Feral Labs would have told her father that she had not survived the surgery.
Alternatively, if her health wasn't dire enough where her father would risk such a surgery, then perhaps Feral Labs would request to have her sent to a facility and then there would be an "accident" staged where Iona was "killed."
Just some ideas to kick around. Main thing to remember is that Moreau would never have sucha direct line that could be traced back to him.