N.H. Rev. Stat. Ann. § 231:107

Any such town may settle with the claimant its proportion of the damages claimed; and the settlement shall be a full discharge of its proportional share of the damages and costs as against both it and the other towns; but the same shall not affect the claimant's rights against the other towns or either of them, or be put in evidence in any suit commenced by him against them, except in proceedings relating to the adjustment of contributions between the towns, when final judgment is to be entered up.