They need to make sure people are aware when booking a flight that underage children need a passport from US to Canada even though the parent is a Canadian citizen. Apparently birth certificates are not enough. We had to book an American flight to Seattle and cross the border by car where just the birth certificates will work. We were almost stranded at DFW airport, out of pocket for $1000.00. There is no reason that we couldn’t have gone through customs at Vancouver airport with mom’s passport and kids birth certificates. Both children were born in USA. They can travel by car across the border with just birth certificates. That should have been told to me when booking the flight.