hi pal,
had a wee look at the census details for barbieston.
looks like the thom family were running the farm in 1841 and indeed in 1851, there is no mention of high or low.
with the pettigrew family living in the outhouse.
by 1861 there is now mention of a barbieston mill in dalrymple and i reckon there may be houses attached to the mill.
the mcintyre family sem to have taken over the running of the farm. and there is the mention of the priests house by 1871, but still no mention of low barbieston. i concentrated my search in coyleton only, as by 1871 auchinleck is also mentioned.
so your 3 towns are coyleton, dalrymple and auchinleck.
trying to help
Joe