Jules I am going over old posts, and I hope you have found your answer already to the question you posted here. In case you have not:
In practices with multiple providers, each eligible provider (EP)is registered with CMS EMR Incentive program. The payment for each provider goes to the practice designated in their payment profile with CMS. When it comes time to attest (deadline is in Feb 2012 for reporting year 2011), attest for each provider and the money will get sent to the office who receives their payment.
I've attached
THIS LINK to the CMS website on the matter of registering EP's.