Hey there, Amber!
According to the official
Disneyland Resort rules, wagons, including stroller wagons, are not allowed inside the resort. This includes both of the Wonderfold wagons.
Amber, I recommend that you bring a double stroller, or
rent one after you arrive. If you choose to bring your own stroller, just make sure that it is smaller than 31 inches wide by 52 inches long.
Currently, double strollers are available for rent at $36 per day, although prices are subject to change.
I just know that you will have a magical vacation, Amber.
See you real soon!
Sarah B.