Interestingly, when children are added to a p5 canvas or a CanvasClass, they are hidden.
The code that created the sketches below, added several children to the pink and light blue canvas using the "same" code. Then it used the child method to obtain a list of their children. Notice the output is the same for the p5js canvas and the CanvasClass. Then just to prove it works, a new CanvasClass was added to the light blue CanvasClass as its 4th child.
The p5.js file: child.pjs
James Brink, 6/23/2020