http://www.flyertalk.com/forum/Forum1/HTML/007461.html

One to One
CO <--> GR
YX <--> GR
UA <-- GR (UA won't transfer out)

One to Two
GR --> HH

6.7 to One
HH --> GR

CO has recently severed it's transfer relationship with HH, leading some to speculate GR could be next.