TN family members consists of spouses and children. Thus, a mother, aunt, cousin, brother and so on are not considered a TN family member for admission purposes.

The TN visa-holder’s spouse, and unmarried children under the age of 21, may also enter the United States accompanying or following the TN visa-holder, and these individuals are referred to as Free Trade Dependents (“TD”). However, the family member must demonstrate a bona fide spousal or parent-child relationship to you.

Spouses and children cannot work while in the United States in TD status, but they are permitted to study.

http://www.heydary.com/blog/the-tn-visa-entering-the-united-states-as-a-canadian-or-mexican-professional