Changing the Maintenance View

Z_V023 with additional fields. The view V023 is started by transaction SPRO at Logistics - General > Logistics Basic Data: Material Master > Material > Define material groups.

I would create an append structure on T023, with your own fields. Create your new view Z_V023, and use table maintenance generator to create the Maintenance View. Modify the programs created by table maintenance generator, so that only your additional fields can be maintained, and so that the user can't create or delete records. Any other field maintenance, and creating/deleting records should be done through the standard Maintenance View.

This way, you keep your customisations completely seperate from standard SAP, and you are not modifying SAP tables and data.