When Miranda was on Nashville Star, the judges were singer/songwriter Charlie Robison (then husband of Emily Robison of the Dixie Chicks - the guy "Cowboy Take Me Away" was written about). music historian and writer, Robert Oermann, and Music Row business woman, Tracy Gershon (currently managing Natalie Stovall and the Drive).
(I've posted a video of them, judging Miranda in the duet thread)
I think Miranda and Blake Shelton first met when they were asked to perform the Shelly West and Lefty* Frizzell parts in the duet "You're the Reason God Made Oklahoma" (which has also been posted earlier in another thread). I think that was the same occasion as the above Carrie duet
Carrie and Jamie O'Neal were performing the Reba McEntire and Linda Davis parts in that duet
Edit - * sorry - I meant David Frizzell (they were brothers!)