There is a bit of information on Ancestry about Dora Quinn and Martha Fivecoat Quinn but the most compelling information that proves Martha is the mother of your Dora Quinn is the Texas Birth Index of 1903-1997 that shows Dora's birth date 12 Dec 1913 in Galveston, TX. The Texas Death Index, 1903-2000 lists Martha Qinn's death date as 2/10/1914. There are census records of Martha and Charles Quinn in 1910 but of course, Martha dies in 1914 so you won't find Dora and Martha together in the census records.
I also found Martha's death certificate on ancestry which gives her cause of death as pneumonia. The other wife of Charles Quinn is Georgia Bell Culpepper, so Sally doesn't fit the facts. You might look at Dora's death certificate and see who else is mentioned on the document.
Got IT!!!!!
I believe there are 2 Dora Quinn's in TX. One is the one mentioned above and the other is Dora Mae Quinn in 1900 and 1910 census records in Jackson County, TX. This Dora Mae's mother and father are Sarah Quinn(Sally) and David Quinn. These two Dora's might have been confused by researchers.
As it turns out, Dora Mae Quinn is the aunt of Dora, daughter of Martha Fivecoat. There is a family tree on ancestry with many old pictures. I was able to see Dora's death certificate and D.M is also named as Dora's father. So Dora Mae's father is David Quinn and mother is actually Sally Bryant Quinn. Charles Quinn was Dora Mae's brother.
