Part of what I found interesting is when it was said that they can know all the cars in the county in 24 hours, so they know the cars in question are from outside the county. To me, this just adds to the idea that Jayme was probably not the target. The vehicles of anybody who might be in her extended circle would be known by now. The only reason I know of that can support the idea that Jayme was the target is that she was taken rather than just killed on the spot, but there are other viable explanations for that, not the least of which is DNA. There is no evidence of online activity that would suggest any other explanations. (Unlike the 16-year-old in Wisconsin who had an on-line relationship with a guy from Colorado, who then insisted on coming on getting her, for example.) It is possible that Jayme was the target, but I still don't see it as likely.
We have absolutely no evidence of any internal familial issues between Jayme and her parents, or between DC and JC. I think going that way is just going down a rabbit hole where there is nothing to find. By all accounts, they were a close-knit family.