She is getting ready to tie the knot to Reba McEntire's stepson and she wants someone special in her life to marry the couple. Blake Shelton is not only going to sing at Kelly Clarkson and Brandon Blackstock's upcoming wedding -- but he will also be performing the ceremony. Kelly and Brandon announced their engagement in December but have yet to set a date. Blake is close with both Kelly and Brandon because Brandon is Blake's manager. Meanwhile, Kelly is reportedly recording a Christmas song with Ronnie Dunn.