Have you checked the records on
www.scotlandspeople.gov.ukI note the trees you mention, Abigail is noted as Abigail McConnon Mckinnon,
Some records state they had 17 children in 17 Years, Robert died age 54 in 1841. The trees state they married in 1812 Lesmahagow but no record on SP.
CONNON ABIGAIL ROBERT CONNON/AGNES BROWN 25/02/1826 Lesmahagow
MCCOWAN WALTER ROBERT MCCOWAN/AGNESS BROWN 08/08/1819 Lesmahagow
Oldest son, and the others seem to be on SP, surname spelling, McCowan, McCouan, McConan, and Abigail is the only one Connon. None McKinnon.
Sadly no marriage for a Robert of any name to Agnes Brown on SP 1800 – 1850
However:
MCKENNON ROBERT Age 75 (1766) Died 29/04/1841 Lesmahagow
Colin