You are going to have to sue them in the magistrates court for the value of the damage because the magistrate did not make an order for compensation.
Do you have insurance? If you do you are best to claim and give the insurer their names and leave it up to them.
Otherwise you have to sue them.
Being minors you may have difficulty as they will not have any money, but the process in WA is as per the following link.
I hope this makes sense and is of assistance. If there is nothing further
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