Va. Code Ann. § 15.2-4221

The commissions of any two planning districts and a majority of the governing bodies of the localities comprising each district, upon finding that the community of interest, ease of communications and transportation, and geographic factors and natural boundaries among the localities of the two districts are such that the best interest of the localities would be served, may by resolutions concurrently adopted vote to merge into one district and request the Department of Housing and Community Development to declare the districts so merged. Upon such declaration, the commissions of the two districts shall be merged into one commission. The commission of the new district thereupon shall organize as provided in § 15.2-4203; however, nothing shall prevent the commissions of the two districts which are to be merged from agreeing to the terms of such organization prior to their vote to merge.