Just to note in 9.1 there is a new Fulfillment Management module (SYS 42W)which I think addresses this area. I know you are on Xe and this does not apply directly, but you can see if a consulting firm with knowledge of this new module will retrofit this into your system so at least when you upgrade your rules will match what JDE does and maybe you can setup the new module and eliminate the customization or at least reduce it.
Or use it as an example of one benefit of an upgrade if it seems to be what you need;]
Just an FYI in case you were not aware the new module addresses this type of issue.
According to the documentation the module will do the following:
The purpose of the JD Edwards EnterpriseOne Fulfillment Management system is to fulfill orders in
accordance with criteria agreed upon between you and your customers. The JD Edwards EnterpriseOne
Fulfillment Management system fulfills orders based upon criteria that you set, which enables you to:
• Generate priority order scores and then match available inventory to open orders.
• Use service level rules to define fill rates for customer orders and ensure compliance with stated fill
rates before releasing orders.
• Implement an automated process that fulfills inventory to orders based on the rules.
• Review the fulfillment quantities and make necessary changes.
Hope this helps.