One other item, when traveling with children from US to Canada and back into US, Highly Recommend that you also have copies of the children's birth certificates as you may be asked to prove that they are actually yours by either country. It's to me happened before, when I took the family from DTW to Buffalo through Ontario. (I'm glad someone had pre-warned me) From what I understand, some parents that are in a custody dispute/battle will take the kids north of the border to elude authorities.