N.C. Gen. Stat. § 20-279.9
The security required under this Article shall be in such form and in such amount as the Commissioner may require but in no case in excess of the limits specified in G.S. 20-279.5 in reference to the acceptable limits of a policy or bond. The person depositing security shall specify in writing the person or persons on whose behalf the deposit is made and, at any time while such deposit is in the custody of the Commissioner or State Treasurer, the person depositing it may, in writing, amend the specification of the person or persons on whose behalf the deposit is made to include an additional person or persons; provided, however, that a single deposit of security shall be applicable only on behalf of persons required to furnish security because of the same accident.
The Commissioner may reduce the amount of security ordered in any case if, in his judgment, the amount ordered is excessive. In case the security originally ordered has been deposited the excess deposited over the reduced amount ordered shall be returned to the depositor or his personal representative forthwith, notwithstanding the provisions of G.S. 20-279.10.
N.C. Gen. Stat. § 20-279.9