I have Bahee Christian b 1739 d/o Thomas Christian & Ann Cowin as my ancestor. Somewhere, somehow, many years ago, I picked up that "Bahee" was an earlier form of "Margaret". Years later I found her mother's will 1765 called her "Bridget" (figured out by process of elimination of all the other sisters) and her father's will of a year later mentions "David Gelling husband of Bahee" as one of the overseers of younger siblings. So the "Margaret" connection was wrong, which took me about 5 years to figure out. This demonstrates that one has to be careful about these things. Thanks to Frances for her help in resolving these questions. And thanks to technology to make better information available.
Since we're on the subject of evolution of names, I also have Judith Quayle (1774-1845) as my 3xg-grandmother. I spent 2 days years ago trying to find her at Salt Lake City to no avail. I did not know that "Judith" used to be 'Joney". Thanks to Donna Douglass, I now have her more or less figured out as Joney Quayle bp 18 Sep 1774 at Kk Michael d/o David Quayle & Jony (Judy) Cannell. It seems the name "Joney" evolved to "Judith" sometime in the 1780s or early 1790s. My Judith Quayle married Charles Kewley 1798 Braddan and was always "Judith" as far as I knew. I suspect (but don't know) that "Judith" then evolved to become "Jemima" and then that name died out in the 1800s. I base this on Joney/Judith's daughter Catharine (my 2xg-grandmother) having two tries at the name "Jemima" for her daughters in 1840 and 1842.
I'm curious about other names that evolved and/or died out. "Donald" became "David" became "Daniel"? "Mariod" became "Mary"? I wonder the reasons why? I suspect it was because of evolution of language and literacy. My apologies if this is already discussed somewhere and I've missed it.