we buy cars for cash nj

Can a parent take the money from the bank account of a child for their own use?
My son has had a bank account since birth. During our divorce his father insisted on having in mind that the 50/50 split so they could start their own for him. The money is deposited into an account and have had deposits of cash gifts, graduation gifts and mowing money the child has been given or gained in the last 11 years. Now is the time you would like to buy a car and have been told that their money is no longer in the bank and that his father and stepmother have taken it and used it for legal expenses. Can you do this? We live in New Jersey.
In New Jersey, not sure about the legality of it. Anywhere on this planet, is morally despicable.
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