Embedded fonts disappearing when loaded into another SWF

I once found that when an AS3 flash movie(let's call it parent) that contained a UIComponent, loaded another AS3 flash movie(let's call it child) that contained a UIComponent with embedded fonts, the component within the child lost its embedded fonts.

I also discovered that if the parent contained the font, then the component in the child was then able to find the embedded font, and all was well.

However, this isn't an ideal situation, because I could imagine that you sometimes want the child movie to be able to operate independent of the parent, manage its own font embedding, or maybe not waste loading time of fonts in the main parent movie that may not even be required if the child isn't navigated to.

I was prompted to revisit this dilemma in a forum post, and it got me wondering what was going on. I can't find documentation to confirm, but I have a theory that once the parent has a UI Component it then tries to take over handling of the list of global Fonts that the child tries to access. This list of global Fonts maintained by the parent, doesn't by default have access to Fonts embedded in SWFs it loads.

However to give the parent access to the font, the child needs to register its font with the global list with:

Font.registerFont(ComicSans); //ComicSans for example

This ensures that when the parent takes over handling of the global list of fonts, it has access to the font the child has embedded.