(a) Where each of a substantial number of recipients is receiving assistance for similar or related purposes from two or more agencies or where two or more agencies cooperate in administering assistance for a given class of recipients, the agencies shall:

(1) Coordinate compliance with section 504, and

(2) Designate one of the agencies as the primary agency for section 504 compliance purposes.

(b) Any agency conducting a compliance review or investigating a compliant of an alleged section 504 violation shall notify any other affected agency upon discovery of its jurisdiction and shall inform it of the findings made. Reviews or investigations may be made on a joint basis.