Section 6B. Not more than 1 counsel assigned or appointed under section 5, 6 or 6A shall be paid for representation of a party in civil proceedings pending in any trial court under paragraph C of section 23, section 24 or 29B or sections 39E to 39I, inclusive, of chapter 119 or section 3 of chapter 210. The chief counsel of the committee for public counsel services may permit an exception to this provision in extraordinary circumstances, such as the pendency of separate actions in distant counties on behalf of a client.