I have all of Dale Clark's fan novels, they are really excellent!
Did his latest novel end on a cliffhanger, or were the major plot points resolved?
as I recall the Ross novels were "official" too and they spent a lot of time talking about someone named "professor veno" who was I think Liz and Roger's creepy brother. what's he up to these days?
it was never revealed, on the series, who Vicki's parents were. that's really the beginning and end of it.
This is why, if the real Dark Shadows is ever to return, it needs to differentiate itself from all of these other shows that are "inspired" by it. Because they just keep coming...