Hi Jean
We corresponded a number of years ago. In fact I found emails dated 2006. I'm no further forward than I was then as regards confirming the parents of Alexander Dykes and Marion Borland.
Have you seen the Loudoun Parish Burial records? There's an entry as follows:
"an infant child of Robert Dykes weaver in Greenholm Son of Decessed Alexr Dykes Greenholm was buried on 20 Mar 1846."
This goes some way to confirming that Robert was the son of Alexander. Alexander died in 1844.