Yes, I expect that he might not have been born in Chester County as we know it today. Perhaps border changes, perhaps the adjoining County? Who knows. But sometime in early January, you and I need to communicate and to "hatch a plan". You have sent me some information on our family but perhaps we could update and share what we have as a prelude to my trip.
Although the will written by John Ross which names his daughter Elizabeth Alexander and her husband James (and his daughter somebody Jamieson) sounds like a good match, I am still open to the idea that this could be another family. James and Elizabeth and Ross and Alexander were such common names floating around that region at that time!
I do have some ideas based on tax records etc about possible relationships, but they are still in the realm of ideas with absolutely nothing to corroborate them with documents.