N.H. Rev. Stat. Ann. § 204-C:31

Issuance by the authority of one or more series of bonds or notes for one or more purposes shall not preclude the authority from issuing other bonds or notes in connection with the same purpose or purposes, but the proceedings under which any subsequent bonds or notes may be issued shall recognize and protect any prior pledge or mortgage made for any prior issue of bonds or notes unless in the proceedings authorizing such prior issue the right is reserved to issue subsequent bonds or notes on a parity with such prior issue.