OK - I found the census that indicates John Wilson, wife Sarah, with Jane, Elizabeth and Agnes. I don't see the sons Quintin or George. Certainly is possible that they adopted him.
Here is an except from my GGM MacKenzie's letter that she wrote my grandmother regarding the family:
"On the other hand, I knew Grandfather Wilson for many years before he died at the age of 77 years. He stayed with us from time to time. He had 3 fingers missing on the right hand- some accident early in life. He was twice married. His first wife my Mothers Mother {Jane/Jean Wilson b 1833}, was Sarah Park of New Cumnock. She died early when mother was 8 years old, & left 2 boys & two girls. Mother was the oldest. He married Elizabeth Beattie some time later & had a large family of 3 sons & 3 daughters, who all grew up to manhood & womanhood . They were all very broad shouldered strong men & mostly worked in the blast furnace, except uncle Andrew who preferred the army & to be over 80. Served for years in India- some of the family born there. His wife is still living in Kilmarnock. He was a Sgt Major & served a long time in the Orkney Islands. Used to write me regular. Was a great lyric & sent me lots of poems-I used to quite a bit on my own we were young once too. They were also musical & Grandfather & Uncle Quentin were preceptors in church in the old days when there were no organs. Uncle Quentin was mothers full brother Nearly all of them worked in Wishaw. Strange as it may seem , near where Dad’s mother lived & my uncle Q lived in the same house later-- tho I did not know that then. Dad & I visited him there just before we were married."
This would put the death of Sarah Park around 1841. I have been unable to find their marriage bann or death records of Sarah.
I found out how to go to different households - I did find a George and Jane Park (b 1781/1786 respectively), and further down I found another George and Elizabeth Park (1766 and 1771) - quite possibly Sarah's grandparents. Unfortunately the records in New Cumnock aren't the best, with apparently many records missing.