I'm also interested in Catherine, Christian and other Dalgarno children living in Quartalehouse in 1841. You may have noticed that Keith Webster age 3 lives in the household. He is the (illegitimate) son of Agnes Dalgarno (born 1809, daughter of George Dalgarno and Jean Stevenson) Keith Webster is my GG grandfather.
Did George re-marry and have more children? There seems to be a significant age gap between Margaret and himself. Any information on the members of this household gratefully received. Sorry I can't be of much help to you.