Notwithstanding the provisions of §§ 13.1-675 and 13.1-855, any corporation that operates any plan pursuant to the terms of this chapter shall have a board of directors consisting of no more than fifteen members of whom a majority shall be subscribers to the plan who are not providers of legal services and not employees or officers of any plan. This section does not apply to a plan operated by a group of attorneys except as provided in § 38.2-4403.