Cost object for price change of project stock

Hi folks,

We do need to change the price of project(WBS) stock value, and for the offset accuont we found that the cost object is determined based on the Business delivery from the PL in MM03. not based on the business area matained in WBS. But for PPV account of GR, the cost object is determined based on the business area maintained in WBS.

Our requirement for price change of project stock is that the cost object of the offset account should be determined based on the business area from the WBS.

Anybody can tell me why the price change of project stock follow the different logic and any setup I missed?

Regards