This sounds right, except that I had read online that John Valiant Therrell (husband of Dora) was the son of John Therrell and Edith Ringo (rather than William T. and Elvy Ward). However, they did have John Therrell as the son of David Therrell and Anna Thompson.
This is what my great-aunt told me some years ago:Dora's husband died in Mississippi, leaving her with three young daughters, two of whom were named Cora and Virginia Mae.(I could probably come up with the name of the third from my father.)Dora took the children by herself by wagon to Texas.
Virginia was married in Fort Worth Co. to Harry Hatcher.Virginia in turn divorced when she had three young daughters, and worked as a stenographer and telephone operator, often staying with her sisters in Fort Worth (where my grandmother was born) and San Antonio.No one has ever mentioned that they had a brother.
Dora was described by my great-aunt as a "noted horticulturalist," whatever that means.In a travel memoir, my grandmother spoke of Dora as a very religious old lady in a severe black dress, who disapproved of her traveling to West Africa by herself.This was in the mid-1920s, so it seems Dora was still alive at that time.
Do you have any further information on the Therrells, Wards, and Thompsons?Are you sure that John V. Sr.'s parents were William T. and Elvy Ward rather than John and Edith Ringo?