DNG: Force default attribute value or force user to update value after copying an artifact?

We have migrated our database from legacy DOORS and copied over a legacy object identifier as an attribute to DNG for historical reference so that existing requirements reference in bug reports and test specifications are maintained. However, when an artifact is copied, and other fields are updated as required, unless the user notices that the legacy ID needs to be deleted, then it too is copied, resulting in artifacts with duplicate legacy IDs. There doesn't seem to be a way to set attributes to read-only, and setting a default of "N/A" or blank only works if you create a new artifact ab-initio. Is there a way to force the default value, or force the user to update this attribute, when copying/pasting an artifact? Any other suggestions???