26 C.F.R. § 1.672(c)-1
Section 672(c) defines the term "related or subordinate party". The term, as used in sections 674(c) and 675(3), means any nonadverse party who is the grantor's spouse if living with the grantor; the grantor's father, mother, issue, brother or sister; an employee of the grantor; a corporation or any employee of a corporation in which the stock holdings of the grantor and the trust are significant from the viewpoint of voting control; or a subordinate employee of a corporation in which the grantor is an executive. For purposes of sections 674(c) and 675(3), these persons are presumed to be subservient to the grantor in respect of the exercise or nonexercise of the powers conferred on them unless shown not to be subservient by a preponderance of the evidence.
26 C.F.R. §1.672(c)-1