Thanks to all you for your input.
I agree - the PO Event Tracking just does not appear to be able to handle the task of managing budget amounts, especially when considering different fiscal years. Too bad.

Steve, your solution of using JobCosting with PO is nice, and I see that it will work over fiscal years as well.

The issue that I am concerned about is that the users for this application are not Adagio power users. If there are a number of rules and steps that have to be performed from time to time, I am concerned that they may get messed up.
For example, every time that they would adjust the Budget values in the GL (which I know will happen), they would have to reimport or update the values in the accompanying JC Estimates.