Howdy, Stephanie! Thanks for bringing your question to the Disney Parks Moms Panel.
The Canadian promotional tickets are such a great value so I'm glad you will be taking advantage of that offer. You are correct that proof of Canadian residency is required to purchase the tickets and to activate them at the gates. Currently, the only acceptable forms of identification are your Canadian passports or NEXUS cards. However, you will only need to prove residency the first time you activate your tickets, so you can keep that passport in a safe place during the other days of your visit. Also, the 4-year-old will not need to provide identification, just the adults.
While we are on the subject of 4-year-olds, I have some tips for traveling with children that age since my daughter will turn 4 this year. First, measure his/her height at home and then research which
attractions he/she will be able to ride. Once a child reaches the 40" (or 102 cm) mark, many attractions become available to them if they are interested. Also, have plenty of snacks on hand. It always seems like my child is "starving" while we are waiting in line for an attraction or to meet a character, so having a backpack full of goodies is a great idea. You can also stop by one of the many
fruit carts at the parks to pick up healthy snack options.
I hope you and your family have a magical visit to the Disneyland Resort!
-Linda M.