I read your response to Sandra, looks like you do have quite a bit of info on this family. If you can ever pin down where John's father owned that tract of land, when he sells any of that land his wife should be relinquishing her dower right, so you can learn her name, no maiden name, but even first names helps to narrow down the searches. And, names of witnesses to transactions may be kin. But, I have a feeling you already know this.LOL
I did a little playing around with searches on GenWeb, GenForum and you probably already realize if the family came from Germany the surname might get a little "misspelled" from time to time. Or, John may even have shortened it from something like Hargarly etc. I see Sandra found some VA information. Also keep in mind for that early many immigrants were coming in through PA first, then dropping down into VA or MD. I'm working on a possible ancestor in Frederick Co, VA who has in the inventory of his estate, 1642, PA and NJ monies. Which leads me to think he came down from the area where those two states are neighbors.