The date details and place name (Abernethy) you mention that show on David's birth cert under Elizabeth Greenhill's name should be date and place of parents' marriage. This info began to be included on Scottish birth certs from the early 1860s.
Can't see anything for the marriage on SP at all post 1855. Could it be 1853? If ever you find the images from SP hard to read due to faintness of image or a similar issue, you can always contact SP, tell them what the problem is with the relevant image ref. and they will send you via email an enhanced image. Can make a big difference. See
www.scotlandspeople.gov.uk/content/help/index.aspx?r=1210Monica
PS: You have the beginning of the trail now back to Catherine Reddie...for another day!
