ActionScript 3.0 :: Combining Document Class With Timeline Code?

I've written a game in Flash using timeline code like this:On the main timeline:

Code:

stop();
include "includes/mySourceCode.as";
init();

Then,in mySourceCode.as I have a set of functions (including init(), of course).I know this technique of coding is frowned upon by many,but it was what I learned when I started out with Flash and it has always worked well for me. It also means I don't usually have to bother with importing classes to make most methods work as I guess they are all 'built in' to the main timeline already.

The problem I have now is that I have got the game sponsored, and the sponsor needs me to include his preloader, which is a document classfile.So I have his preloader working, and once loaded it tells the main timeline to proceed to the next frame, where I have my usual code as above - which now doesn't work.Firstly, it can't find my include files because it is now looking in the document class folder instead of the main .fla folder it usually looks in.Secondly, once I have moved my include files to the same folder as the document class, it gives me around 70 errors about undefined properties and methods, and things not being'compile time constants' whatever that means.

I am guessing that for some reason, since there is now a document class, Flash is no longer importing all the classes it usually does automatically for me - so could it be that I need to go through my whole game and figure out the class import paths for all the methods I have used? Or is there an easier way to get my code working how it was before without having to change it? If I do impoort all the right classes, should it work then or will I still face problems?