Hi Frances,
Checking out Family Search I found 4 children to a Henry Kitson and Eliza Dalgarno all at Saint Nicholas, Aberdeen.
Henry Ketson (spelling as online) chr. 10 Feb 1842
Isabella Dalgarno Ketson( ") chr. 23 Nov 1840
Elizabeth Kitson chr. 11 Jan 1845
Hellen Blackhall Kitson b.7 Dec 1847 chr.21 Dec 1847
Henry Kitson and Elizabeth Dalgardno (spelling as online) married 13 Sep 1839 at Old Machar, Aberdeen.
Elizabeth Dalgarno could not have been the daughter of the John Dalgarno shoemaker whom you discovered on 1841 and 1851 Census

His age on 1841 is recorded as 25 (I can't find him on 1851

). She is old enough to marry 2 years earlier in 1839.
It's proving to be really hard to link all these Dalgarnos together!!