As of Dec 9, 2016, Tiffany has 38 Geni DNA matches. Since there is no good way to sort by highest quality match, I will work from oldest to newest.
First up is Susan F. As luck would have it, this is an adoptee. I have been in contact with Susan's husband, who is helping her with her DNA results. This is a match on chromosome 5. It is a paternal match for Tiffany.
Since so far I can't find a common ancestor, I'd like to take this opportunity to explore Alexis McMillan. Things are a bit confused here. Bernie told me that he believed she had been in Boston, MA as a nurse, and that she had a son before she married, with an unknown father.
Her marriage to Joseph Riggs lists her parents as Murdock McMillan and Myrtle McDonald. She is listed as aged 23, and the year of the marriage is 1934.
There is another Lexis McMillan but she is born to parents Dan A. McMillan and Flora Burns. This Lexis does go to the US where she is a child's nurse in 1930. I can't find another Alexis with the parents Murdock and Myrtle. The problem is, the Lexie who went to the US was still there in 1940...
There is an Alexis McMullen born in Cape Breton on 18 Sep 1909 to a Murdoch McMullen and Myrtle Morris. I wonder if it is possibly she who married Joseph Riggs. The fathers name is right and the mothers first name. Murdoch's mother was Alexis McDonald, and the names on the marriage record may be confused.
It appears that in 1921 Alexis McMullen was living with her grandparents, although she is listed as a niece instead of granddaughter?
I did a bit of research on both families. Maybe I will find a DNA match that helps me locate the correct Alexis McMillan.