I found my answer on the LDS Familysearch.org site that Sarah Ellen Vawter did indeed marry William R. Donaldson after the 1870 census in Illinois, Washington County, Arkansas. This couple moved to California and their last child of four: Willie Josephine Donaldson was born in July, 1879 in Red Bluff, Tehama County, California before she returned to her parents home in Illinois, Washington County, Arkansas. Have no idea what happened to William Donaldson.
Sarah Ellen (Vawter) Donaldson returned to Sherman, Grayson County, Texas where her siblings had settled and married William G. Campbell and had three sons and a daughter Ruby before 1900.
In 1920, Sarah Ellen (Vawter) Donaldson-Campbell, widow, was in the Cleburne, Johnson County, Texas census. I assume she is buried in the Cleburne City Cemetery, but no proof as yet.
Our research continues on Willie Josephine (Donaldson) Richardson and her family which includes my cousin.
That is all I have at this point.. Thanks for you answer.