Haw. Rev. Stat. § 572B-10: Unions performed in other jurisdictions.

A legal union of two persons that is not a marriage under chapter 572, which was validly formed in another jurisdiction, and which is substantially equivalent to a civil union under this chapter, shall be recognized as a valid civil union in this State and shall be treated the same as a civil union entered into in this State regardless of whether it bears the name civil union; provided that the relationship meets the eligibility requirements of this chapter, has been entered into in accordance with the laws of that jurisdiction, and can be documented.