24 CFR 103.202: Notification of respondent; joinder of additional or substitute respondents.

(a) Within ten days of the filing of a complaint under § 103.40 or the filing of an amended complaint under § 103.42, the Assistant Secretary will serve a notice on each respondent by certified mail or by personal service. A person who is not named as a respondent in a complaint, but who is identified in the course of the investigation under subpart D of this part as a person who is alleged to be engaged, to have engaged, or to be about to engage in the discriminatory housing practice upon which the complaint is based may be joined as an additional or substitute respondent by service of a notice on the person under this section within ten days of the identification.

(b) The Assistant Secretary will also serve notice on any person who directs or controls, or who has the right to direct or control, the conduct of another person who is involved in a fair housing complaint.