Hi Ashok,
Once you have delimited the control, we prefer you to create a new control with the required validity.
Although from the backend transaction "GRFN_STR_CHANGE" you can extend the validity of the entity
if that is newly created and not used by any of the entity in the product. But this can cause data inconsistency.
So we always prefer too do the master data changes from front end only to avoid any data inconsistency issue in future.
Regards,
Silky