Plan the household’s actual arrival and departure around the assignment rather than assuming a short project needs no status assessment. A spouse and unmarried children under 21 may qualify as L dependants; each needs the appropriate entry documents and admission.
Compare the project calendar with each admission record
A supplier moving a meeting does not extend anyone’s authorized stay. If the spouse plans to work during the visit, check their own valid L dependent status and the appropriate spouse-specific I-94 evidence: the qualifying spouse’s employment authorization arises incident to that status. It does not arise from the supplier contract, and it does not apply to an unmarried dependent child under 21.
Keep the family’s departure plan and any proposed employment consistent with the actual authorization. Fix the household's document set before the assignment is booked, not after. For each person travelling, hold their own entry document and their own admission record, and confirm that the dependent classification on it is the one the plan assumes.
A spouse's employment authorisation is generally incident to valid status and is evidenced by that spouse's own record, which is why a copy of the principal's paperwork answers nothing about it. Hypothetical example: a household books travel around a supplier review and learns afterwards that one dependent record was issued in a different class from the rest.