I am also related to the family in question and have done my own research and also have work done by a family member, a history professor, who spent time in courthouses, pouring over documents and records from the mid to late 1800’s, and he listed the woman’s name a Sarah.
I went back and looked at the census reports from 1850-1930. When the woman was a girl and living with her parents, she was listed as Sarah. As an older adult, from 1900-1930, Sarah lived with her brother and then with another relations and she is enumerated as Sallie. The death certificate lists Sally. The birth year is the same for both which leads me to believe that Sarah and Sally are the same person.
As I explained to the woman who e-mailed me, Sally is a common nickname for Sarah. My own grandmother was named Sarah and was called Sally and Sal by my grandfather.
Often, when I see older census reports, parents do not use the proper name, but a nickname. Like most folks doing genealogy, we want to enter the proper name into our database, but might not know how to translate the nickname to the proper name.
Back when I first began working on my roots, I found an excellent resource book by Emily Ann Croom1 for sale at the genealogical library where I was working. There is a good chapter on names and I am going to copy some of them here in case there are other researchers out there that might like to know how to translate nickname to proper name. I'm certain there are probably more than what is listed below--but it's a beginning!
Mamie, Molly, Mollie, May, Masie, Polly, Minnie, Moll
Maggie, Peg, Peggy, Meg, Midge, Madge, Daisy, Maisie, Meta, Greta
Marty, Martie, Mattie, Patty, Patsy
Beth, Eliza, Liz, Lisa, Lizzie, Lisa, Lise, Elsie, Betty, Betsy, Bitsy, Bess, Bessie, Libby
Ella, Ellie, Nell, Nellie, Nelly, Nora
Sarah--Sallie, Sal, Sadie
Frances--Fran, Frankie, Fannie
Annie, Nan, Nannie, Nina, Nancy
Kathy, Kate, Katie, Kat, Katy, Kay, Kitty, Kit
Millie—Amelia, Mildred, Millicent
Hettie—Esther, Henrietta, Hester
Patty--Patricia, Patience, Martha, Matilda
Eveline, Emeline, Carolina, Angelia, Selina, Selena, Helena, Paulina, Magdelena
Bell(e)--Arabella, Anabelle,Isabel, Rosabel
Nora--Honora, Honoria, Leonara, Eleanor
Dora--Theodora, Eudora, Dorothy
Nell--Ellen, Helen, Eleanor
Delia--Cordelia, Adelia, Ledelia, Adele
Jane, Virginia, Janet, Jennette, Jennifer
Allie--Alice, Aline, Alene, Aletha
1. Emily Ann Croom, Unpuzzling Your Past: A Basic Guide to Genealogy, Second Edition, Betterway Publications Inc., White Hall, Virginia, 1989, page 23-27.