I am not sure I buy the idea that Xana's father changed any locks. Unless I am a mistaken, he is not on record saying that anywhere here. That infor came from her mother, who has been somewhat disconnected from the situation for some time apparently. We do know that the dad had made a comment early on about Xana having changed a lot, for the better, since going to college and having her relationship with Ethan.
Don't throw rocks at me, but is it possible that Xana's dad told her mom, in a phone call, that "she had changed a lot", and she mistook it for that "he had changed a lock"?
Can anyone verify, with a source, where it was said by anyone other than Xana's mother, that a lock had recently been changed? JMO