So it has to be either Aretha Franklin, Bread or Carly Simon. The Sinatra GH2 and the unreleased Jethro Tull M.U. no longer belong to WMG, and the Doors already came out.
I can't think of another GH album that was a Quadradisc, unless it's an artist that wasn't originally on WEA.
In either case, this would be a great Quadio! The Aretha, an original 2010 Quadio, would sound even better on BluRay, the Bread Best of is a highly sought after SACD and the Quadio would most likely put it to shame, and the Carly would be super as it contains quad tracks from her second album which never got a quad release.
To me, that's a win-win-win, no matter what the case.