My research hints strongly that the Sarah Rothwell (Rothwell-543) that married my great grandfather, Harrison Elswick, was the same person as a Sarah Rothwell born in Bath County (later Menifee County), Kentucky in 1859. Here are the clues:
1. [Sarah] Rothwell appears in the 1880 Census as Harrison's wife. The Census indicates she is 20 years old and born in Kentucky. This is consistent with the birth record of the Sarah Rothwell born in Bath County, KY, on 9 December 1859.
2. Sarah and Harrison Elswick name two of their children William and Agnes. The Sarah Rothwell born in Bath County has parents named William and Agnes.
3. Family remembrance is (and records confirm) that Harrison moved frequently in his adult life, no doubt in search of work. He moved back and forth between Kentucky and West Virginia and it is quite conceivable that one of his earlier wanderings brought him to Menifee County where he could have met Sarah.
So ... my question: At what point can I/should I conclude that the earlier records for Sarah Rothwell refer to the Sarah Rothwell of the later records? If not, where can I look for further data? I have exhausted FamilySearch.org and Ancestry.com for online sources.