The whole thing about Jebez's life in the 1790s was never properly fleshed out. The appearance of Peter Bradford's ghost happened very last-minute. It was supposed to be the ghost of Paul Stoddard, but Dennis Patrick had another commitment and wasn't available for those shows.
I always thought Dan insisted on the story snippet cited above out of sheer spite because Alexandra had defied his wishes and refused to come back to the series. Dan did sometimes dictate specific story developments, according to interviews with the writers. They'd protest that the developments conflicted established continuity or simply made no sense, and he'd say something like "I can always get somebody else to write this show, you know." I think this kind of thing explains why the series got more and more chaotic over time. Lela Swift began to play this game when she became producer in 1970, too. The final Angelique/Barnabas storyline was supposedly her idea.
G.