N.H. Rev. Stat. Ann. § 552:6

If the probate of a will is not contested the judge may allow and approve it in common form, upon the testimony of one of the subscribing witnesses, though the others are living and within process of the court, or upon the assent of the surviving spouse, legatees, devisees, heirs at law and, in the case of an unnamed charitable interest, the assent of the director of charitable trusts, without the need for a witness to appear.