The committee shall have power to appoint sub-committees and to appoint thereto persons who are not members of the committee, but F1at least one of the members of any sub-committee shall be a member of the committee. The committee may delegate to such sub-committees any of their functions under Part I or Part IV except their duty under section 3(5) to afford opportunities to incumbents of benefices and vicars in team ministries to meet the committee itself and their functions under Schedule 4.