Assistance rendered under this chapter or N.H. Rev. Stat. Chapter 161 to anyone who is the child born of an unwed minor whose father or mother, grandparent of the child born of an unwed minor, has a weekly income or other resources more than sufficient to provide a reasonable subsistence compatible with decency and health, may be recovered from such grandparent in the same manner and by the same proceedings as provided in N.H. Rev. Stat. § 167:2 and 167:3 for recovery from other legally liable relatives.