(a) In General. - Neither the Secretary nor the Board has jurisdiction under this part over the transportation of property by motor vehicle when - (1) the property is transported by a person engaged in a business other than transportation; and (2) the transportation is within the scope of, and furthers a primary business (other than transportation) of the person. (b) Corporate Families. - (1) In general. - Neither the Secretary nor the Board has jurisdiction under this part over transportation of property by motor vehicle for compensation provided by a person who is a member of a corporate family for other members of such corporate family. (2) Definition. - In this section, "corporate family" means a group of corporations consisting of a parent corporation and all subsidiaries in which the parent corporation owns directly or indirectly a 100 percent interest.