In such stories, I am always amazed how blind relatives are. They knew that kidnapper for ages, they new his behaviour, thoughts (it is not hard to predict elder peoples intentions and moves, as with age, they turn to more and more to children like), they probably knew his addiction to gambling. I mean they could have foreseen that grandpa is intend to do something weird. I see one major problem here - why Yuan family did not do anything with his gambling addiction?