This article shall not apply to any corporation operating or maintaining a hospital service plan or medical service plan, participation in which is limited to its employees and the employees of other persons or corporations with which such corporation may have contracted to provide such services; provided such contract is not entered into for the purpose of evasion of the terms and spirit of this Code. As used in this section, the term "employees" shall include members of the families of employees.
Okla. Stat. tit. 36, § 2618