If you are taking minor children outside of Canada, and travelling without both parents in attendance, you need to take some additional steps before you travel. In order to prevent international child abduction, you will likely be asked to show that you have the consent of both parents to take the children outside Canada. The most efficient way to do this is through the use of a consent letter.
The Government of Canada provides a template letter that has all the basic requirements. It is recommended you use this template or one provided by your lawyer to reduce the chances of travel difficulties. It is also recommended that the non-travelling parent be reachable by telephone at the time you plan to leave Canada in case border officials wish to verify the letter or its contents.
To find out more about travelling minors, please visit https://travel.gc.ca/travelling/children/consent-letter.