A multi-site role can affect where the household lives and how often the principal travels. Review any immigration implications of those trips separately. TD permits study but does not authorize employment, so do not assume a spouse can offset travel-related household costs by taking a job.
Choose a household base before the assignment starts
Pick where the family will actually live rather than defaulting to the first project site, since school enrolment and housing commitments are harder to unwind than a travel schedule. If a spouse intends to work, that requires separate authorization and its own analysis with counsel. Each family member's status stands on its own, and steps differ by nationality.
Weigh TD against a status the spouse would hold in their own right, since that difference decides whether household income can continue. TD lets a spouse or child accompany the principal and study, but it does not authorize employment, and no amount of travel by the principal changes that. A spouse who wants to work needs a separate basis of their own, obtained through its own process and on its own timeline, which may not align with the principal's start date.
Where children are involved, measure the school year against the assignment period rather than the reverse; an admission granted for less than the academic year raises a renewal question that is easier to plan for than to discover midway through.