I am now fairly certain that each of them had a sibling who were also a married couple!
Andrew Arbuckle bc 1829 in Cambuslang was also the son of Andrew Arbuckle and Mary Shaw
Peter Casey had a sister named Janet Casey bc 1832.
( I posted the 1841/1851 census for the Casey family earlier on this thread)
Anne,
I haven't scrolled back to check but is this Andrew & Janet Casey?...
1881 Address Nimmos’ Land, Blantyre
Parish Blantyre ED 6; Pg 29 Line 12 Roll cssct1881_202
Andrew Arbuckle 49 (1832) Coal Miner b Cambuslang
Janet Arbuckle (Spouse) 48 b Cambuslang
Archibald Arbuckle Son 21 b Bellshill
Marion Arbuckle 17 Dau b Bellshill
Andrew Arbuckle 15 Son b Wishaw
Margaret Arbuckle 13 Dau b Motherwell
Mary Arbuckle 10 Dau b Motherwell
Janet McGill 19 Dau b Bellshill
John McGill 3 Months G/Son b Motherwell
Annie