So the writers came up with the idea to use Peter Bradford's ghost instead and Jeb killing Vicky in 1796.
Yes! I had completely forgotten about that big threat of Paul Stoddard's ghost coming back and killing Jeb. So that really DOES explain it. Vicky got offed because Dennis Patrick got another acting gig! Oh the horrors!
Well, let's be grateful. Joan Bennet could've been offered a temporary stint somewhere else and they would've had to write off her character as being buried-alive/sent-to-Wyndcliff/off-on-a-Bloomingdale's-sale-of-the-century-shopping-spree and who knows what "plot twists" they would've come up with then.