On the "Hamilton" issue, I just used the GEDmatch kit number you provided, with their One-to-Many DNA Comparison. It's not the 1st match, but rather (as I said) the first match WITH A GED file. That shows up as a blue "GED" link in the fourth column of the results. You click on that link, and the click on the "Pedigree" link at the top of the page, when that result comes up, and it shows the pedigree for that match. Your married name is on your GEDmatch results page, and there's a family tree on Ancestry with the family members you cited, which is named with both your married surname and your maiden surname, so that's apparently your pedigree (maybe it was done by a daughter?). Anyway, it showed a Hamilton. Not the exact same one as the guy with the GEDCOM file, but he doesn't go back very far - just to a great-grandmother named Hamilton. If he went back another generation or two you'd probably see a matching ancestor (unless you're related a different way, and the Hamilton is just a coincidence). If you told him about YOUR Hamilton, and about the match, it might actually help him go further back on that part of his tree.
But getting back to the Hollingsworths, you're looking for 1st cousins, and living ones at that, so that's a whole different "ball game". While millions of people have taken the DNA tests, that still only amounts to about 1% of the population, so the chance of a 1st cousin, or even one of their children, having done one is pretty small. I have 17 living cousins, and was surprised to see one of them finally pop up in my results in recent months. They have dozens of children - mostly adults - and none of them have popped up at all.
So to find out about them, just see what you can find out about those who are deceased on places like Ancestry.com, and then use that info to find obituaries that will tell you who the living are, and where they lived at the time, and see where you can go from there. Expand your "net" to include the first cousins of the people you're interested in (whether they have the surname or not), because they might know how to contact the people you're looking for. Also contact active researchers that have these people on their trees, if any, because they might know a helpful thing or two also. Newspapers can be useful beyond just obituaries, if people are old enough. Ancestry has SOME that you can search, but there are other sites that are more comprehensive (like newspapers.com). Another good source for the living is stevemorse.org (his "Birthdays and Related Persons" option, in particular).
Just because one relative is unreceptive, it doesn't mean they all are, so don't let that one bad experience discourage you.
But to do a Hollingsworth DNA confirmation, keep in mind that you do not need somebody actually named Hollingsworth. You just need a Hollingsworth descendant, most of whom undoubtedly do not carry the surname. If you can find descendants of a couple of your Hollingsworth gt-gt grandparents' children that you match, you're set! You just have to do enough research to find out that that's what they are, if they don't have an extensive enough tree, themselves. Once you notice a DNA match that has one of your ancestors, then you can identify many of the others who are also related on that side of your family by using the "Shared Match" option on Ancestry.
Good luck!
