question.
Going back to Iraq, Petraeus "worked for" CENTCOM but really never did. When Fallon tried to impose the chain of command he was asked to retire. Today, Odierno works for Petraeus - probably more so than the latter worked for Fallon - but Petraeus is letting odierno run his show, at least in public.
Afghanistan is more complex. On the one hand CENTCOM is the higher HQ; on the other SACEUR. Managing the Petraeus - Stavridis relationship must be interesting to say the least. I'm not even going into the commander/ambassador relationship - we've done that before Suffice that Petraeus is consistent in his public treatment of his two "subordinates."
My personal view is that the UCP does not serve us well when we set up a 4 star command in a theater. The theater commander is operating above the operational level and is analogous to a GCC with political as well as military responsibilities. We should,I think, treat him as if he were a GCCand make all the GCCs supporting commanders. What we call it is less important than how we do it,

Cheers

JohnT