Why do you think Cackle hatchery ever had any Voter or Hyman stock?
First they did not develop their own American Dominique strain independently from other existing strains. Secondly they did not have to acquire from some other commercial hatchery stock which I take is implied by your question.
Positive information is by word of mouth from Fred Farthing and Mark Fields. Latter provided birds to former from which I sourced some of mine and as I understand it Mark provided birds he had to multiple parties including Cackle Hatchery in an effort to preserve lines in the hands of multiple parties. Last communication I had with Mark was at his home about 4 years ago. I think he may still be the most knowledgeable about those lines in the Midwest. He did not give me any leads into American Dominique's on the east or west coast.