Restricting BP Grouping values

We are implementing MDG-Supplier and we are using the Supplier UI.

When a user selects the field BP grouping (in Supplier Details UIBB) there are several values (Std SAP values + the ones created for the project)  in the drop down.

Does any one know of a simple way of restricting these values to just the ones created for the project ?  (FYI - We don't want to delete the SAP std delivered values as they will show up after an upgrade )

Thanks,

Vinay