Because the school called 911 upon discovering that they couldn't account for Kyron, doesn't mean they told the Hormans that. The Hormans may have been enroute to the school, expecting Kyron to be there, then arrived to find out that the school hadn't located him, but instead called 911.
Whereas a number of articles have said Terri called 911, I've been unable to find anything from the LE statements/documents that supports that. I generally rank LE statement/documents higher so far as accuracy/reliability than articles. That's why I think, despite the news reports, that Terri did not actually call 911.
We also have Kaine's email in which he said the Hormans called 911 "in concert" with the school. I'm not sure (physically) how one would do that. Perhaps upon reaching the school, the secretary with the Hormans on speaker phone called 911? I don't know.
I'm still chewing all this over, now that we've put more of the pieces all in one place.
I think we can put together a timeline for this time period, which would at least give us points at which we can say we know this person was here, we know this person called that entity, etc. It helps me to look at things on a timeline because whereas it won't tell me what did happen, it usually tells me a few things that couldn't have happened, and helps me get a better feel for what is most and least likely to have happened.