How to Map this requirement?

Dear All,

Following is the scenario... 

I am having one Business Group, 1 Legal entity and 5 Operating Units..

1st Operating Unit: Administration

2nd Operating Unit: East Division

3rd Operating Unit: West Division

4th Operating Unit: North Division

5th Operating Unit: South Division

2,3,4 and 5 Operating Units are not having right to create any invoices. All Payments of 2,3,4 and 5 Operating Units are done by "1st Operating Unit: Administration".

Following is the Structure of Chart of Accounts

1. Company: Following are the values...01 Administration, 02 East Division, 03 West Division, 04 North Division, 05 South Division

2. Department

3. Accounts

4. Spare 1

5. Spare 2

But i we have already 4 Operating Units are defined.