i am happy they are doing this, i know there are a lot of GPN fans that like Heart and want Grace to sing a Heart song.  I am personaly not a fan of Heart, and particularly just don't like the song Barracuda.  I do like a couple of thier ballads from the 80s from when I was growing up, but I havnt heard any in a while.  The dance music artist Kim Sozzi recently did several remixes with different DJs for the song "Alone" and it is pretty slammin.  

I don't know what the Diva's thing is all about but my guess is GPN has their own set (however short it may be...), as does Heart...then Grace maybe will sing with Heart.  I bet they do Barracuda together. Either way great cause and great idea from VH1