I don't believe there is a mix up.
I think Swinfield Hill (b around 1743 or 1758--I have seen both dates) in Chester Co. PA, son of Robert Hill, who married Martha Van Bibber or Martha Vidder) in Burke Co. NC is the grandfather of the Swinfield Hill who married Nancy Mullins (on some lists possibly erroneously said to be Nancy Lyons), daughter of William and Jane Stanley Mullins of Franklin Co. VA.
I think the lineage goes Robert Hill + Violet Linus > Swinfield Hill + Martha Van Bibber > William Hill + Nancy <Elizabeth??> Mullins > Swinfield Hill in Franklin Co. VA where he married.
This line is so confusing this may be nothing more than a massive brain cramp on my part, but please let us compare notes.
I am trying to put together an e-mail list serve for the descendents of Robert Hill. Anyone who is interested in pooling information, please contact me. It's difficult to reach many contributors to these threads because of the illegibility of the email addresses and because email addresses change frequently these days.
Thanks and best,