回复：回复：You are legal to stay in US since you all Canadian citizen

>>>老公失业，TN作废，太太和孩子的TD也做废，应在多长期间找到工作保持合法？
>>>-- Doesn't matter. You can stay in US since you all are >>>Canadian citizen. You just need to apply TN/TD again if >>>you find new job.

Are you sure about this? If you lose the job, the TN/TD status will be invalid, and you can't stay in US on invalid status. You can leave and re-enter as visitor. You may even be able to apply for change of status directly to USCIS service center by mail, but I am not sure about this.