Can you post some pictures of the 3 other multihorned ? Last time I saw a female with the powder blue like yours, was many years ago on a website from Australia(down under), it also was a multihorn lacking tall spikes. I wonder what part of Hispanola this variance comes from ?
Regarding the Austrian breeder, his resources seem to be unlimited. I would be surprised if his lewisi are anything but pure.
To catch the blue on photo, get the iguana very warm, then mist with a water spray bottle right before taking the photo. The below 2 photos are the same iguana. In the photo without my son, the iguana was misted.





