You'll need two witnesses for your proxy marriage, plus an officiant. MONTANA CODE ANNOTATED § 40-1-324 Declaration to be acknowledged and recorded The written declaration of marriage provided for in 40-1-323 shall be attested by at least two witnesses and formally acknowledged by an official authorized to administer oaths in the state of Montana. The filing of the declaration with the clerk of the district court in the county of the residence of the parties shall serve as an official record of the marriage of the parties. En. Sec. 87, Civ. C. 1895; re-en. Sec. 3633, Rev. C. 1907; re-en. Sec. 5726, R.C.M. 1921; Cal. Civ. C. Sec. 77; re-en. Sec. 5726, R.C.M. 1935; amd. Sec. 2, Ch. 276, L. 1959; R.C.M. 1947, 48-132.