You are welcome.
I did not know I was looking for a Thomas Gallaher, tomorrow I will try to look through the Gallaher family history I have again for that name. I just looked through it and only saw one Joan name in it. Must be a different one from yours although the dates are very similar.
I understand your search better now. I have been trying to do the same with some of my family when I can. It sure adds up. ($$$ !)
As I understand it a match can mean at any time in history almost, depending how close the match is, etc. Odd things come up. My paternal direct DNA line didn't match the surname either. (Doesn't mean they are not out there...)
PS of course the results are only as good as the database, if not enough people in that line have done it, results will be paltry and incomplete. (If there is another male not in that direct sub-line if it were me I'd test them also.)
PPS - LOL - there is a user name here 1_bgallaher you might try to private message him. He is the source of the Gallaher family history I have. Never know you two might compare clues and end up with some info.