It may be possible to confirm family relationships with Rebecca by comparing test results with other carriers of her ancestors' mitochondrial DNA.
However, there are no known mtDNA test-takers in her direct maternal line.
It is likely that these autosomal DNA test-takers will share DNA with Rebecca:
Gasaway-70 and Gassaway-22 do not represent the same person because: I'm rejecting this merge because according to the sources you cited on Rootsweb, the Rebecca who married James Evatt was the daughter of Nicholas and Sarah (Unknown) Gassaway, not James and Elizabeth (Scruggs) Gassaway.
Gasaway-70 and Gassaway-22 appear to represent the same person because: Hi, when I created my profile page for Gasaway-70 no selections popped up I suppose because I spelt it wrong but when I added her father two Nicholas Gassaways came up that are the same person with two different Rebecca profiles the 3rd identical Rebecca is Gassaway-224. So if it's possible for you to, could you merge Gasaway-70 with Gassaway-22 and then also Gassaway-224 we can get all three together on the same page, Thanks!