Exactly…, you’ve hit on the exact problem.  If America came through first nothing would happen, and the IPC’s would be wasted since Russia can’t collect without a capital.  So if the enemy blitzes into the territories, they immediately assume control and the IPCs, but if an ally blitzes the money is still lost.

What would make sense is to transfer control upon entering a vacant territory.  For example: if the UK takes western europe but on the following turn Germany annihilates with the UK leaving no troups in Western Europe (but control still with the UK) and then the US deploys troups there, the US should assume control.

Now if the UK still has troups in Western Europe when America deploys there troops there as well, then of course control would stay with the entrenched party (UK).

Scenario:
US blitzes through Manchuria to Kwangtung leaving no troops in Manchuria.  US now has control over Manchuria.  Later all of US troops are destroyed, yet Manchuria is still under US’s control.  If Russia places troops in Manchuria.  Can Russia take control (IPC’s) of Manchuria?

The point is, it seems silly that I need to wait for a Japanese troop to move into Manchuria just so I can move my Russian troops in there to take control for Russia.  If the territory is empty, you should be able to decide who controls if you are on the same team (provided you can actually move troops there).  This becomes very important for IPC management.

The problem is further agrivated if someone looses their capital.  I.E. if Russia losses their capital can US start taking control of Russian territories as it Blitzes through them?

Bottom line: If I have troops in friendly occupied territory (that was originally hostile) I should be able to take control, if it is agreed to by both friendly powers.  Your thoughts?