The die has been my primary theory for several threads now.
Consider: very active boy, atypical environment. Foster daughter, easy. Crayons and paper may entertain her quietly for hours. Wm, busy. We love that about him, but not everyone is equipped for that.
He's 3. The mouth is a pocket. Especially if your Spiderman ensemble has none.
So... we learn that Wm isn't good at rolling dice. He'd rather throw them. One might choose then to take away the dice and engage him elsewise. ME, I'd have encouraged people-zoomies, in the backyard where I could see him. Wear him out.
Now, if said adult did try to remove the dice, a clever little klepto might go for the mouth vault.
How many dice were recovered? Did anyone ever compare that to how many may have been in play?
Because the next series of events may have been most unfortunate, and not predictable.
If Wm ran from the deck with a die in his mouth, if Wm even attempted a cry or a roar or an exclamation of any kind, the die could have been sucked in on the precipitating inhale.
Still, that alone to me would warrant desperate aid. Unless no one went after him for several long minutes in which case the silence
would be the alert.
If Wm died from choking unattended on a die, and you had been taking photos just prior, of him throwing dice and potentially pocketing one behind his baby teeth, and you didn't remove the deadly die from his mouth, would you describe those photos as Wm's last moments with the die that killed him? (I mean if you were going to conceal and lie about his death.) Or would you. attach a different story to those photos? We were playing and happy and safe and roaring....
I don't think there was an intentional death here at all. But I do think the pressure to hide it was gargantuan.
JMO