Lo and behold, lie #3 - older sib speaks for younger sib - has become the truth.
By way of background, Jeremy is 22 months older than Bradley, and Jeremy is about as typical as they come in terms of childhood development. I knew Jeremy would be a great big brother to Brad. He's nurturing and caring, and likes to lead in play. Jeremy is also a good peer model, with good social skills and language. What I didn't call is what a great friend Brad would be for Jeremy. Jeremy always seeks out Brad to play. It's not a one-way street, at all. They're like two peas in a pod, and I couldn't be happier.
They often play together, sometimes unattended, and inevitably there's some sort of conflict. After all, they are ages 4 and 6, so play requires some referee-ing.
Into the room I barge.
The problem: Jeremy does all the talking. Perhaps I'm facing Jeremy instead of Brad when I demand an explanation. Perhaps I'm at fault here too.
I've noticed this a lot lately. Sometimes Jeremy reports aches and pains to me, on behalf of Brad. And sometimes, Brad needs help (wiping) in the potty, and rather than holler, Jeremy will come get me.
Now that this revelation has dawned on me, I'm going to make a conscience effort to elicit speech from Brad and tell Jeremy to shush when he goes into spokes-brother mode.
I'm not sure what else to do by way of remediation here. But at least now I know what lie #3 is all about.