The only real person on the Island that could help to make a connection (besides the all knowing others) would be Sawyer. He had that drunken chat with Christian in the bar before he died. Who knows what all they talked about. Christian spoke of his regrets about his son and how he had failed as a father, possibly he spoke of his daughter also. Since we know he traveled to Australia to make contact with her. So, maybe Sawyer will be the key.