Never heard of these people. Where in Appalachia do they live, what kind of last names? Now that I think of it, Granny always did make possum soup for colds. The Beverly Hillbenjies.
And from among them there arose a king who would lead them to freedom and glory. They called this king "Elvis".
Use the "Web Search engine" (Google, Yahoo!, or Ask.com) to check out the information. There is a considerable amount of anecdotal information, and some of the "success stories" of the more prominent members of this interesting subgroup of American settlers (Ava Gardner, Abraham Lincoln, and of course, Elvis Presley are all rumored to have been descended).
Remember, the correct spelling is "Mellungeon". They apparently all originated from a relatively small gene pool, and intermarried with several of the local Indian tribes (Cherokee, Choctaw, Creek)