I am having a hard time with her taking him to school, then telling him to come to the island and killing him. I can't get this to fit....
Yes, that's the toughest part of the puzzle. All the signs now point to her having been responsible (and to LE and Kaine believing she was responsible). Perhaps we'd understand it if we had access to all the interview and questionnaire information that LE collected but hasn't released. But it's apparently been confirmed that both Terri and Kyron were seen at the school that morning, at some time after quite a few other people had already arrived at the school too, and that Kyron was not seen again beyond 9:00 or so.
It's hard enough to imagine how she could have gotten him out of and away from the school after that, *especially* on a morning with an unusual number of parents being at the school, without anybody seeing (but maybe someone *did* see, and LE knows that, even though we don't).
But it's almost beyond comprehension that she could have planned in *advance* to be able to get him out of there somehow, after making an appearance to create an alibi. She obviously knew a lot of other parents would be there, and had no way of controlling who would stop her in the hall as she left with Kyron, and ask "is he sick?" when wondering why he was leaving with her, or who would spot her in the parking lot as she was getting into her truck and run over wanting to talk about the kids and their science fair projects. And the idea that she didn't have it all planned in advance, and either did it impulsively, or took Kyron to the school that morning with the idea in her head that she'd *try* to sneak him out of there after they'd been seen and then take him somewhere and kill him, but just try again some other time if it didn't work out today . . . well, those scenarios just seem beyond plausibility.
Like you, I haven't been able to put together a remotely plausible scenario under which she could have:
1) been with him at that tiny school with hordes of parents and children who would recognize both her and Kyron (apparently confirmed to have happened), and
2) then gotten him out of both the building and the parking lot (which would have been crowded with other parents leaving around the same time) before the time that at least one child (the one whose idiot grandmother had him talk to the media) says he was noticed missing from class by a teacher's aide.
If she could somehow have managed those two steps, the rest was easy, but I'm not getting how she managed those two steps without being seen doing Step 2 (but again, maybe LE knows that she *was* seen doing Step 2). Maybe she just asked Kyron to come with her to get something from the truck before going to the classroom, and had some cover story prepared for both him and anyone who might spot them, as to why they were going out to the truck. That's the "plan on trying to kill him today, but postponing it to another day if it doesn't work out" theory. Technically plausible, but just seems awfully far-fetched.
Then again, if any of us had speculated before Elizabeth Smart was found, that she might actually be walking around Salt Lake City, being taken to parties and restaurants by her kidnapper, while wearing a face veil, we'd probably have been laughed off of WS for the preposterousness of our speculation. I'm thinking we may well be in for another round of finding out that some wildly implausible scenario is in fact what happened with Kyron. And maybe there will yet be an Elizabeth Smart-type miracle, and Kyron will be found alive and healthy in a well-concealed underground bunker on Sauvie Island. Until a body is found, there's still hope.