"However, I do have DNA connections to Edward McGill Neilson/Catherine Banks (B 1793) from the Invernesk area. "
Kazza,
Can I as you something about your DNA links to this couple?
Do your DNA connections stem from more than one child born to this couple?
My husband's ancestral aunt, (daughter of his 4x great grandparents) married one of their sons.
This son and his wife emigrated to the US and became LDS members.
Being LDS families, many descendants have undertaken DNA tests.
So far, my husband has 37 DNA matches to their descendants and the amount of shared DNA for each definitive relationship ( most are 4-5c ) is a bit too high. IE 40cM-95cM
I have never found any other connection, and no DNA matches with any other child born to the Neilson/Banks couple