No. A commercial extension does not itself extend immigration status for the principal or dependents. Review each person’s actual status period and the steps required for the intended stay. TD also does not authorize employment, regardless of how long the employer’s project continues. TD dependants may study, but they may not work.
Track individual dates
Record the principal’s and relatives’ documents and planned activities separately. Do not assume every family member received the same validity period or follows the same procedure. A later project phase should prompt a status review before the household relies on continued stay or work.
Derivative status is narrower than most households expect. TD is available to the spouse and to unmarried children under twenty-one of a TN principal, and to nobody else — a parent, an adult child or a sibling needs a basis of their own. TD dependants may enrol in study, full-time or part-time, but they may not accept employment in the United States, and no length of residence, no school enrolment and no employer goodwill alters that. Remote work for a Canadian employer is a question to put to an adviser on the actual facts rather than to assume is outside the rule.
Two things are routinely conflated and must be kept apart. The principal’s own eligibility rests on citizenship of Canada or Mexico, a position matching a listed professional occupation in the USMCA appendix and that profession’s credential, with the work done for a US employer rather than a business the applicant controls. A relative’s permanent resident card does nothing for the principal’s case and nothing for a dependant’s.
Hypothetical example: an orthotics clinician plans a move with a spouse who intends to keep working and a child who turns twenty-one during the second year. The spouse needs an independent basis for any US employment, and the child’s TD eligibility ends on that birthday whatever period the parent was admitted for.
Dependants are inspected at a port of entry or preclearance with proof of the relationship and of the principal’s status — whether the principal was admitted at the border or through an approved Form I-129. Track each person’s admitted-until date separately.