The parents are not criminally liable, but they are civilly liable for the actions of their child in that if the parents of the cards' owner can show that the parents of the child who stole the cards did not properly supervise or monitor their child (that is, they were negligent or unreasonably careless in supervising their child), those parents can be held resposible for the cost of the damaged or missing cards. Their liabiity would be based on their own negligence as parents--not directly on the child's actions. So you have to show that under the circumstances, something *they* did was neligent or careless to hold them liable.