Chicago Meet and Greet

Do you have any idea how to get Band Meet & Greet passes?
I keep seeing Carnival of Madness post pictures from them.
We are going to Toyota Park / Chicago show.
I am hoping to have my 12 and 13 year old meet Arejay and Joe.
My 12 year old has been drumming since 5 and my 13 has been playing guitar since 5.
Halestorm is their favorite band.
I played guitar for many years, but my playing days are just around campfires now. It's cool to see my sons so into it now and I hope to be able to arrange this for an unfogettable day for them.
BTW: Are there backstage passes for sale?
Any help is appreciated!
Thanks, Joe