Definitely do not use parent.parent.parent etc. At the very least keep a reference to the instance with the var or function you need.

The document class is the class which will be associated with the root. Properties and functions defined I'm the document class will be available in the main timeline, and by calling them with the root reference (after casting).

What you have described with the convert function is a static utility class. There's nothing wrong with those, but try to keep them stateless.