In 1841, David and Sarah are both working away from home:
David is at Hurlford, Riccarton, Ayrshire, age 20, Engine Keeper. Living with the family of Alexander Vallance, whose son, same age as David is also an Engine Keeper.
Sarah (20) is a Female Servant in the household of Alexander Williamson, Farmer, at Beach, Straiton, Ayrshire.
There is an extracted (so reliable) marraige on the IGI for Sarah Findlay to John Hood, 13 Jan 1850 @ Straiton.
Sarah and John Hood are on the 1851 census at Mye, Stoneykirk, Wigtownshire, where John is a Dairyman, age 43. No children as yet.
IGI shows 2 children born to the couple: Agnes Hood, 28 Mar 1855 @ Tradeston, Glasgow, and William Brown Hood, 12 Mar 1858, Blythswood, Glasgow.
1861, Sarah and John are living at 147 Hospital Street, Govan, with sons John b. c1852, and William b. c 1858. So looks like little Agnes did not survive (unless she is living with grandparents etc?), plus 8 lodgers. John snr, was born Ochiltree, Ayrshire and is now a Warehouse Porter.
All the best.
Ellen.