Each person's status is assessed separately. A spouse and unmarried children under 21 may qualify for TD, with steps that depend on nationality. They were admitted for this visit on their own terms, and a TD arrangement would be a distinct step, not an automatic follow-on.
Handle each family member's status on its own
Marriage, age, and citizenship all matter to whether TD is available, so check them rather than assuming the household moves as one unit. A child who is a U.S. citizen does not need TD at all. Note too that TD permits study but does not authorize work, so a spouse who expects to keep working, including remotely, needs that question answered before the family plans a longer stay.
TD does not authorize employment, and the principal’s credential does not become the spouse’s qualification. Marriage certificates, birth certificates, and any translations belong with the person they concern, alongside their own admission records. A genuine spouse job offer needs its own lawful work basis. The employer’s financial arrangement does not provide the spouse an independent immigration category. Record each person’s citizenship independently; Canadian permanent residence is not Canadian citizenship and does not create TN eligibility.