Shared Operating Units Problem in Organizational Hierarchy

I have situation where customer have one Cost Center dimension shared between few Business Units. When I try to create this structure in Hierarchy Designer I have problems. On the top I define Legal Entity, under Legal Entity I have few Business Units and below them few Cost Centers per each Business Unit. This business has few locations; among others use one person in all those locations to do some work. They want to restrict accountant to enter only correct person in appropriate location. In order to do that I created few above described hierarchies and attached them to Account Structures. Problem is when we try to create Journal Entry everything works fine until we get to Cost Center level (workers) it look like hierarchies simply cancel each other (because they share one same Cost Center). I spent last few days trying to find solution for this problem. It would be great if someone could help.

DJ