A suggestion, and three questions:
1. I see that the Drath's character model was drastically changed between Altarian Prophecy and Dread Lords. Couldn't you incorporate that into the storyline? Maybe the beefy-looking Drath guy from AP could have been from a warrior caste/clan/position. Or to show the deviousness of the Drath, he was just a fake image to depict their race as seemingly slow and dim-witted all brawn and no brain lizards, to throw off the humans in first contact.
2. Were any of the other races' avatars drastically changed between games? I don't think so, other than the Arcaens look more mysterious and glowy in a bit of a Warcraft III style.
3. Storywise, why are the Drath good even though they are so devious and underhanded?
4. Why are the Altarians good even though they kicked out the Drath? Was the dispute between them ever resolved in Dread Lords?