For the purposes of this subsection, service of the notice shall be by personal service or certified mail, return receipt requested. After initial service is effected, additional service upon a party shall be satisfied by regular mail to the party's last known address. In any child support enforcement proceedings subsequent to an order, upon a showing that diligent effort has been made to ascertain the location of a party, notice of service of process shall be presumed to be satisfied upon delivery of written notice to the most recent residential or employer address on file with the state case registry.
HRS § 576B-207