Just to add to the mess...Pete has a ...nephew, I believe, named Nick Seeger. Nick played around New England and the mid Atlantic states as I recall. I have one old album of his, on Biograph, I think. "Sail on, Flying Dutchman" was the titile. I heard he had a kids album, but haven't heard much about him in years.
Peggy Seeger plays out occasionally in Asheville N.C., where she lives. Used to live across the street and a few houses up, although I've not met her.