I have been following this case closely. In my opinion I think the focus of motive still needs to remain on Jayme. I am not one of those people believing she had some internet boyfriend/ secret boyfriend. I do think however there might have been a man that spotted her in real life or online and was obsessed with her.
If the perpetrator was after the parents for some reason I think that Jayme would have been found dead that night.
It makes no sense to go to the house for retribution of any kind, find Jayme, and decide then to take her along.
This is my opinion, and only an opinion. There are so many unknown factors in this case atm. If and when we get more information my opinion may change.
If we play the odds, I agree the most likely event is that Jayme would have been killed if the parents were the target. However, I think back to the Bible/Freeman case in OK where Freeman's father was the target and the killers took the two girls anyway instead of killing them on site. A big difference here is Freeman's father was involved with marijuana and owed some less-than-outstanding citizens money. We don't see that here.
I originally thought this might be a 17-21 year old who was obsessed with Jayme, now I'm thinking this just as likely be anyone from 17-45 years old. I'm hoping LE finds something by going back 60 days in phone and social media history, but I doubt it. I just don't believe someone obsessed with Jayme would be communicating and then abruptly stop 30-60 days before, but who knows.