In a customer environment, we have custom (Owned) data items that have been added to customized versions of both the header and detail tables of a base HD table. In the absence of being able to add these as Common Fields (can’t add fields to the Common Fields definition of a customized version of the HD table), what is the best and most reliable way to make sure that the custom fields in the detail table always match the values of those same fields in the header table?