This article defines "unauthorized use"
http://www.creditcards.com/credit-ca...arges-1279.php
"Federal law defines it as "the use of a credit card by a person, other than the cardholder, who does not have actual, implied, or apparent authority for such use, and from which the cardholder receives no benefit."
I would say in this case the cardholder is receiving a benefit, because if his son would have won money, he is cashing out back to the method used to deposit.
Also, "some card companies, including Bank of America and Capital One, specify that fraud protection applies only when credit cards are lost or stolen."
In this case, the card was neither lost or stolen.
Let me ask you this. What do you think will happen when during the investigation it becomes apparent the deposits came from the same household? Don't just say they don't investigate because that's not true at all.