TD dependants can accompany a TN holder and may study, but they cannot work in the United States under TD status regardless of how many turnaround assignments the principal applicant completes.
Understand what TD status does and does not permit
A spouse and unmarried children under 21 can generally accompany a TN engineer on TD status for the length of an authorized stay. TD dependants may enroll in study, including full-time academic programs, but TD status does not carry employment authorization, and this does not change no matter how many separate turnaround assignments the principal applicant completes over a year. A family planning around repeated short U.S.
assignments should treat each TD period as tied directly to the underlying TN period it accompanies, and should not assume that a pattern of several trips in one year converts TD status into something broader. Any family member who wants to work independently in the United States needs their own qualifying status, evaluated on their own facts rather than derived from the engineer's repeated entries.