How to Derive all IBases or IObjects for Business Partner

I have searched the forum but not have not found any threads which deal with this topic.

We are in Discovery for a possible project to implement CRM Service Orders for our Public Works Department. One of their business requirements is the ability to derive all Installed Bases or IObjects for a particular employee.

We know that we can create a Partner Determination Procedure in which the Partner is determined from the IBase, but this is the opposite case. We need to determine the IBase from the Partner.

Specifically, when creating a line item in a Service Order or a Service Confirmation, we need to be able to enter an Employee as the Executing Service Employee or the Employee Responsible, and have the system display a selection list of the IBases or IObjects for which that Business Partner is the Employee Responsible.

This is a major productivity issue for our users. if this is not possible in CRM, we may not move forward with CRM Service Orders.

Is there any configuration or standard functionality which allows this kind of determination? Thank you for any help you can give me.