First, this counterparty is OK to trade physical power.
I just spoke to  Leslie, and she said it was OK to set up "Ameren Energy, Inc. as  Agent "  under one cpy id # for the three utilities and that's how they would trade.
We spoke to Melissa Murphy on the Power Confirm Desk and she is going to set  up a special confirmation template that will add the three utilities names to  the confirmations before they go out.
I think this is how Global  Counterparty already set them up.
If this doesn't compute, let me know...
The Confirmations would then go out as Ameren Energy, Inc., as Authorized  Agent for and on behalf of Ameren Energy Marketing Company, Ameren Energy  Gathering Company, and Union Electric Company (d/b/a Ameren UE).

Ameren Energy, Inc., as Agent