I assume the info you had previously was from LDS.
One of them is probably wrong but who knows which!! The census does have errors sometimes. Although i don't see how Anthony can be mistaken for Thomas, but stranger things have happened!
The list differs slightly form the census
1. HUGH SHANKS - International Genealogical Index
Gender: Male Christening: 14 FEB 1832 Stranraer, Wigtown, Scotland
2. MARTHA SHANKS - International Genealogical Index
Gender: Female Christening: 16 MAY 1847 Inch, Wigtown, Scotland
3. JOHN SHANKS - International Genealogical Index
Gender: Male Christening: 09 JAN 1842 Inch, Wigtown, Scotland
4. WILLIAM SHANKS - International Genealogical Index
Gender: Male Christening: 12 FEB 1839 Inch, Wigtown, Scotland
5. ANTHONY SHANKS - International Genealogical Index
Gender: Male Christening: 26 JAN 1851 Stoneykirk, Wigtown, Scotland
6. HUGH SHANKS - International Genealogical Index
Gender: Male Christening: 14 FEB 1837 Inch, Wigtown, Scotland
7. JAMES SHANKS - International Genealogical Index
Gender: Male Christening: 12 SEP 1834 Inch, Wigtown, Scotland
No Sarah, no Thomas. But there is a Hugh and Anthony. I assumed Hugh had left home already, so i checked the census for him and found a possible,
address, 898 Freugh
Hugh Shanks age 15, unmarried, Errand boy, Servant in the household of Andrew Hannay, born Inch,
This was a farm in Wigtown.The age is slightly out, but then that is not too unusual either.
Hope you find this of help
Amanda