(a) If the employer and the injured employee or his dependents reach an agreement in regard to compensation under this Article, they may enter into a memorandum of the agreement in the form prescribed by the Commission. An agreement, however, shall be incorporated into a memorandum of agreement in regard to compensation:
(i) for loss or permanent injury, disfigurement, or permanent and total disability under G.S. 97-31, (ii) for death from a compensable injury or occupational disease under G.S. 97-38, or (iii) when compensation under this Article is paid or payable to an employee who is incompetent or under 18 years of age. The memorandum of agreement, accompanied by the material medical and vocational records, shall be filed with and approved by the Commission; otherwise such agreement shall be voidable by the employee or his dependents.