You can clone with
No one assigned
This appears to assume that there are never more than two levels of government responsible for a particular issue, and should perhaps be generalised to allow for more levels.
For example, France is sub-divided as état, régions, départements, arrondissements, cantons, communes, tennis courts, and carpet tiles, each of which has its own fiercely competitive administration. "Both" for n>1 may turn out to be inadequate. :)