Hi
The first level WBS will be account assigned. The requirement is to bring all the costs from the lower levels to the top level where the AUC is mapped. So one AUC per project. Fixed assets also in the same level.
I have seen the note in which SAP recommends not to use for performance issues but since I have seen this in other projects and also here the structure will not be very complex. I am planning to suppress the message as suggested above.