Have you considered taking one of the dna tests to help connect your Galloway to others from NC or SC pre-1800s. You could take either the y-chromosome test as a male with the surname or the autosomal dna test that ancestry offers which is less precise but can match with both male and female testers.

i have been working with several other Galloway researchers to try to pin down our Galloway line pre1800 in either NC or SC and some allege that some may be connected to Darlington SC Galloway lines. Autosomal dna research is slow and tedious but as more people use it to supplement paper research patterns can start to emerge.