I have although I am still not able to find my direct ancestors.
Dear Ms. Miller,
Thank you for posting your request on History Hub!
Certificates of Degree of Indian Blood (CDIB) are issued by each Bureau of Indian Affairs agency and are held by the Department of the Interior in the American Indian Records Repository. We suggest that you contact the Cherokee Nation for more details about tribal membership and to inquire about the lineage of Robert and Donald Miller.
We hope this is helpful. Best of luck with your research!
[Information provided by Cody White, Subject Matter Expert]