I just Googled Melungeon, interesting. My grandfather was born in 1879 in Texas but his family came originally from Tennessee. He went back there to visit them a few times. It was his different looks that make me wonder about his ancestry. His last name was Copeland and I have never seen that name among Melungeon names. Wish I had asked him more questions before he died. Isn't it always that way?
Hit the Census records in TN; which counties matter. Census records and associated surnames are fairly easily located online these days. Neighbors’ names in the vicinity, too. They were isolated and even ostracized in the 1800’s, so being in the vicinity of a Melungeon community would likely tell you something.
And, how is little Cookie doing? Still better?