I read the relevant bits in the Berry Dee book about CV.
First, most of what Berry Dee writes about SJL's movements before her disappearance etc seem to be lifted from the AS book, and so does what he writes about CV, he effectively is quoting AS without attribution.
I find Berry Dee's comment on the phone calls CV alleges were made to him to be illogical. Berry Dee claims, and he attributes this to "officers investigating the SJL case", that "Sarah" was phoning the pub to check on SJL and a man she knew SJL to be with, viz. JC.
Now that makes zero sense to me. It's inventing a lot of narrative that is just not supported by any evidence. So we can only take it as a theory that is based on conjecture and trying to make some sort of case for JC to have been involved.
SJL made her arrangement to go to the pub right before she left her office, although it is unclear whether that final call was to KH or CV (CV says it was to him). So for this theory to be right, she would have had to meet with JC, tell him, and he then told "Sarah" since according to this theory, "Sarah" knew that SJL was with JC and that SJL planned to go to the pub. But if this is the case, then (1) why didn't "Sarah" know that the appointment to go to the pub was at 6pm, according to CV (our only witness to this timing)? Why did she phone up so early asking if SJL had been already?
(2) If SJL met with JC at 12:40, how and when did JC inform "Sarah" of the pub story?
(3) If Sarah was told by JC that SJL and he were planning to go to the pub to collect her stuff--remember CV says that "Sarah" was talking about the stuff--why would she need to call the pub to check up on her? Surely, it would make more sense for "Sarah" to call Sturgis and ask them to get SJL to call her if it was that urgent.
(4) "Sarah" must have known SJL rather well to know all this and be so concerned for her to call, and so, given in this implausible narrative she is a friend of JC, she must have been terrified when CV came out with his evidence saying she had called, since "Sarah" knew that she had given CV her number, making her very easy to trace, and hence JC would have been revealed as well. Yet CV has no issues having this story of a potential link with very dangerous people (even though he couldn't have known specifically about JC, he might assume that "Sarah" and her friend, the abductor, were very dangerous). If you were "Sarah" and a mate of JC who you now know abducted and killed SJL, would you not be scared witless that CV gave the phone number you so eagerly gave him to the police? Might you not want to get him to change his story? You definitely wouldn't want him to suddenly recall all this a year later?
To be honest, a main reason for the "Sarah" phone call asking if SJL had "already been" could be to establish that SJL had NOT already been to the pub--if in fact she had already been and something had happened. It's a way of trying to provide a sort of alibi for SJL not having been there yet, because someone phoned up looking for her--thus also showing others knew of these mysterious plans--and CV is able to say that she hasn't been there.