I think the OP is asking do child support payments have to go to the Child Support office, or as they call it in New Jersey, the Probation Department, or can he pay the custodial parent directly. I don't get all the whys of the question, but the answer is maybe... not all states require it. Back when Bill Clinton was in office, he signed an act which gave financial incentives to the states to collect child support money. The act was intended to target deadbeats, but it has the added benefit for the state that they can process non-deadbeats through this system as well and still receive the financial incentives. Overall, that is simpler for the states than doing the hard work of actually going after the non-pays. So many/most states (I don't know exact figures) require payments to go through the state, and through automatic removal from paychecks. You'll have to check for your individual state.
I personally believe that this practice is more evasive than protective. It was a simple matter for dad to give a check to mom, and for mom to cash it. When mom demanded it go through the probation department, it became an automatic debit from his payment, because that is how New Jersey at least works it. I believe that this is an infringement on his privacy, because his employer should have not right to know how many children or how much support he is required to pay, especially since their original decree agreed that he would pay it directly and did so for five years. Additionally, the employer is permitted to deduct $2 a pay period (his pay periods are 2 weeks) for a processing fee, so my husband is essentially paying an additional $52 a year for a "convenience" that he does not want and did not request. The custodial parent is not required to pay any sort of processing fee, so this is patently unfair. I know it is only $52, but over the course of time, that adds up to more, and there is a principal that my husband is now paying for the state for something that he and his ex managed quite well for years on their own.
But, I know that since I am the step, I have no rights in the situation and therefore, I probably shouldn't express an opinion.