It may be possible to confirm family relationships with Rebecca by comparing test results with other carriers of her 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:
Ah, you are concerned about having parents attached to your Rebecca after the merge that may not be her actual parents? If they aren't her parents you can detach them. I don't have good sources for US info so you would be in a better position than I am to find out. Wish I could help more.
Elliot-1504 and Elliot-541 do not represent the same person because: There is no proof that Rebecca was the daughter of Francis Elliot and Abigail Nichols. The only reference noted for the profiles of Francis and Abigail is a link to a Ancestry page (which can't be opened from the Wiki profile). Do we have any proof that Rebecca was the daughter of Francis and Abigail? I have found a marriage records for Rebecca and also a death record, but there is no birth record that I can find in the MA vital records. Thanks!