I hope that I can offer you some suggestions and that I don't confuse you int he process !My own family originates from in and around Carnwath.My GGGrandparents were William Aitkin and Euphemia Guthrie who were married in Edinburgh in February 1802.They had at least12 children who were born in and around Carnwath, Dunsyre and Walston(which are all very close to each other).I have been able to identify Euphemia Guthrie's ancestors with little difficulty but have had major problems in identifying William Aitkin (or Aitken). I have searche hard for William Aitkens who were born at an appropriate time to marry in 1802.I have found two men called William Aitken who might fit with my family or yours.
The first William Aitken, who was baptised September 26 1772 in Dunsyre, was the son of Thomas Aitken (baptised May 21 1749 in Walston) and Janet Paterson.
The second William Aitken, who was baptised May 15 1777 in Walston, was the son of John Aitken (baptised September 12 1742 in Walston)and Marion Brown.
Until you put your message on the Genealogy Forum I believed thet the William Aitken who married Euphemia Guthrie was the second William Aitken as above.[I have found it helpful to see whether the children's names match their maternal and paternal grandparents names.The tradition is that the first born son takes the paternal grandfather's christian name, the second son the maternal grandfather's name ditto with daughters and their grandmothers.] William and Euphemia's children were Isabella 1803not known where she was born [probably named after her maternal grandmother Isabella Farquhar] Thomas1805 born Edinburgh[possibly named after his paternal grandfather] John 1809born Dunsyre[possibly named after his paternal grandfather] Robert 1812born Walston [probably named after his maternal grandfather, Robert Guthrie] Jane 1813not known where she was born Jean 1815b Carnwath Agnes 1817b Carnwath James Tweedie1819b Carnwath William1822b Carnwath Marion1824b Carnwath Alexander Guthrie1825b Carnwath(My GGGrandfather) Euphemia Guthrie1828b Carnwath
I would guess the the William Aitkin who married Helen Somerville in 1802 could well have been the second William Aitken and I shall have to retreat and claim the first William Aitken !
Do let me know what you think.I have tracked both of the William Aitkens back several generations