N.H. Rev. Stat. § 482:71
If an owner or the owners of real estate, franchises, easements and other property affected by proceedings under this subdivision is under any legal disability and is not under guardianship in this state or his residence is unknown or uncertain, the department shall upon application by the municipality, appoint a guardian ad litem, who shall represent the owner in the proceedings. The department shall determine and fix the amount due to any guardian appointed by it for services and disbursements in connection with any proceedings under this subdivision, and the portion of such fee that justice requires shall be payable out of any award that may be made for any land or right of the ward that may be taken.
RSA 482:71
1989, 339:1. 1996, 228:106, eff. July 1, 1996.