When used in this subchapter, unless otherwise specified, the terms—

(a) Family member means (1) a spouse, (2) an unmarried dependent child including a step-child or adopted child, (3) a person designated in official records or determined by the agency head or designee thereof to be a dependent, or (4) other persons such as parents, parents-in-law, persons who stand in the place of a spouse or parents, or other members of a household when fully justified by the circumstances of the hostage situation, as determined by the Secretary of State.

(b) Agency head means the head of an agency as defined in the Act (or successor agency) employing an individual determined to be an American hostage. The Secretary of State is the agency head with respect to any hostage not employed by an agency.

(c) Principal means the hostage whose captivity forms the basis for benefits under this subchapter for a family member.