Kay, I don't have an Eliza Coffin in my database.I usually stick to my direct lines plus siblings.Eliza could have been one of William's grandchildren but I wouldn't necessarily have that.
There were many, many Coffin cousins that moved from Nantucket to Guilford County, NC. I would suggest you look in Volume I of Hinshaw's "American Quaker Genealogy."It covers the North Carolina meetings and you should find a record of Eliza there. Hinshaw is widely available in libraries.
I didn't have Donna Reed either but there are many prominent Nantucket descendents in politics and show business including Benjamin Franklin, Daniel Webster, Richard Nixon, Gerald Ford, James Dean and Richard Chamberlain among others.The Coffins are also well represented in business and other walks of life so if you are descended from Eliza you are from a distinguished line.