So everything was planned from the beginning? About 10 years ago (estimated age of daughter, they probably gave a real age/time frame but I don't remember it*), they sent her to the US, had her get engaged, get pregnant, then leave. They then waited until the daughter got older, set up the whole plan to get him on the island, made him go through all that nonsense just to sacrifice him?
Did they set the plan up right when their honey got "cursed", then decided to wait out however long it took, or did they just set it up "just in case"?
If they were just going to wait it out, you have to think after all those years they would just think there has to be an easier way.
*In fact, I believe Nick cage says something along the lines of "it's been _____ years"