Well, I haven't found an answer to my question yet.
But I did just notice line 4 of atypes.h:
// DO NOT move or edit this file!
woops, ok so I guess I can't do that
for some reason I thought I read somewhere I could edit it as long as I copied it to my work folder...
it must a different include file

so anyway I'm back to square 1
I need a way to store more data for my character entities
I've tried adding a new member to the ENTITY struct but that sometimes crashes the game and sometimes the data is corrupted.
I'm guessing the engine has some hard coded references to the structs that makes editing that file hazardous.

any suggestions?