Exchange 2007 mailbox deleted but user was the organizer for many meetings

a decision was made to delete a user's Exchange mailbox.  Prior to this, the contents of his mailbox was exported to a PST file including his calendar information - it was mistakenly believed that this would retain his meeting information.

His Exchange account was deleted and then a new exchange mailbox was created.  Then the contents of the PST was copied back to the exchange mailbox.

 new accounts were created.  His mail and calendar entries were copied back from the PST into the exchange mailbox.

The trouble is that he was the organizer for literally hundreds of meeting requests.  Can anyone think of a way to allow us to re-link these meetings.  He was the organizer of the meetings and there are dozens of external email recipients that are on email of the meetings (we need to be careful here to avoid causing mass confusion).