That's a tough one. It sounds very promising, but there is no direct tie in between the two families. I'd say its very likely they are connected, but unfortunately, you don't know HOW. I mean if they are indeed connected, you have no way of knowing if they are siblings, cousins, or something else completely. It sounds like a couple branches that I'm researching where I can almost taste the connection, but I can't find quite enough to prove it.

The lack of a DAR application on your side would really make me wonder. I know that some people have no interest in that sort of thing, but you'd think that if one branch of the family had an interest, that someone from the family next door (so to speak) over the course of almost 200 years would have as well.

Did you find any land transactions between the 2 families? That wouldn't show a familial relationship, but it would at least show they interacted. Do you see any transactions outside the family? If not, that would help to show they kept it "in the family" and if there were transactions between the families, that (IMO) would strengthen the connection.

Has your search been strictly online, or have you checked the local repositories? I've heard it said that online resources only account for about 10% of the records available. That's where research becomes actual work, and can get a little expensive. Have you tried the local historical society?