An order under subsection (a), (b), or (c) of this section may be issued only after an opportunity for a hearing in accordance with section
554 of title
5, except that, if the Commission determines that any person who wishes to participate in such hearing is a part of a class or participants who share an identity of interest, the Commission may limit such person’s participation in such hearing to participation through a single representative designated by such class (or by the Commission if such class fails to designate such a representative).