Oh it would be pretty easy with a few agreed upon house rules.
Lets say you're a soviet squad seargent and your partner is a russian wing commander at a neatby base. You're trying to defend a bridge when youy notice some Tiger tanks approaching. You call to your partner for air support, maybe an escorted sortie of Il2's.
I could think of 2 ways of handling the timing of the 2 games.
1 - make CMBB run in real time in the same way that a chess match sometimes has a limited time to make a move - say 5 minutes to every real time set of issued orders and then let IL'2 run in real time. (a typical IL2 flight may take 5 to 15 minutes).
2 - make IL'2 more turn based by simply limiting the flights to taking place every 20 minutes so that you would run off 20 CMBB turns for every IL2 flight.
Either way the question is how do you reflect what happens in IL2 in CMBB? How do you remove units (or add them in the case of a succesful air drop)? And the answer seems to be - you can't.
Still....there must be a way...