When a change is done in the ZCBS hierarchy (creation/change/deletion) of group, it must be performed in all controlling areas (Rules - CO structure): 6 controlling areas in WP1 & 1 controlling area in PF1 + Acetow for the CBS part of the hierarchy.
Start the transaction using the menu path or transaction code KSH2
Double-click
Change Cost Center Group : Initial Screen
In WP1, the structure needs to be amended in each controlling area. Start by setting the controlling area and click on "Extras" then "Set Controlling Area"