Considering how they screwed up with Edith, perhaps it's just as well that they omitted him.
I do remember that Kathy Resch used Caleb in her ongoing serial called the Collins Story. Caleb is some sort of magus who became a recluse after the mysterious death of his wife and son. The family generally avoided Caleb, except for Desmond and Leticia's twins, a teenage boy and girl. The twins had a weird relationship and had moved on from tormenting their siblings and were ready, they thought, for what Caleb could teach them. Caleb sensed their potential for evil and was quite willing to take them as acolytes. Leticia knew that something nasty was afoot and was determined to save her kids. And the story does confirm that Carolyn is a reincarnation of Leticia.
Intriguing, huh? The Collins story appeared in The World of Dark Shadows and Inside The Old House. Unfortunately, when print fanzines when the way of the dinosaur, the saga came to an unresolved end. I don't know if Kathy ever wrote a resolution. If she did, I'd sure love to read it.