Upon amendment or termination of an income withholding order, the child support agency shall send appropriate notice to the income payer. An income withholding order is to be amended by the child support agency when the total amount of money to be withheld is changed by elimination of arrearages or by court-ordered change in amount of child support. An income withholding order is to be terminated when the duty to support ceases and all child support arrearages have been paid. When two or more income payers have been subjected to income withholding orders with respect to a child support obligation, the child support agency shall suspend the income withholding order directed to one or more income payers, provided that the amount of child support withheld by the remaining income payer or payers equals the amount determined under section 14-09-09.30. The child support agency shall immediately reinstate any suspended income withholding order should any child support obligation of the obligor thereafter become delinquent. The child support agency shall provide a copy of the reinstated income withholding order, by first-class mail, to the obligor and the income payer.