Any instrumentality jointly created by the Commonwealth and any other state or states is hereby authorized, upon the granting of like authority by such other state or states, (i) to enter into an agreement with the federal agency whereby the benefits of the Social Security Act shall be extended to employees of such instrumentality, (ii) to require its employees to pay (and for that purpose to deduct from their wages) contributions equal to the amounts which they would be required to pay under subsection A of § 51.1-704 if they were covered by an agreement made pursuant to § 51.1-702, and (iii) to make payments to the Internal Revenue Service in accordance with such agreement, including payments from its own funds, and otherwise to comply with such agreements. Such agreement shall, to the extent practicable, be consistent with the terms and provisions of § 51.1-702 and other provisions of this chapter.