Haw. Rev. Stat. § 393-6
If an individual is concurrently a regular employee of two or more employers as defined in this chapter, the principal employer shall be the employer who pays the individual the most wages; provided that if one of the employers, who does not pay the most wages, employs the regular employee for at least thirty-five hours per week, the employee shall determine which of the employers shall be the employee's principal employer. The employee's other employers are secondary employers. An employer so designated as the principal employer shall remain as such principal employer for one year or until change of employment, whichever is earlier.
If an individual is concurrently a regular employee of a public entity which is not an employer as defined in section 393-3 and of an employer as defined in section 393-3 the latter shall be deemed to be a secondary employer.
An employer who, directly or indirectly, interferes with or coerces or attempts to coerce an employee in making a determination under this section shall be subject to the penalty provided under subsection 393-33(b).
HRS § 393-6