Cbesh,
"sic" indicates how the name was spelt in my record. Yes, Sarah's father was Stewart and to support her 1860 birth I have found a marriage of Stewart Wetheral, father James, to Eliza Brown, father Richard, in Shankill Church of Ireland, Lurgan in 1853. The IGI list other children through the 1860s into the 1870s but nothing before 1864, the official start of Civil Registration of births.
Regards