It wouldn't be a problem with cascading combo boxes because you're coming in from the top. You pick the country first, then the state, province, or equivalent, and then the city. At that point, the city list is already limited to cities belonging to the selected state, which belongs to that country.

If you were entering the city first, then yes, you'd need a way to distinguish between duplicate names, such as asking which Bristol the user means. But that's a different problem from the normal top-down cascading setup.

So if I understand your point,  you cannot list cities in the city table as (duplicates permitted). Bristol Tennessee would be listed as (country) USA, (state) Tennessee and Bristol England would show up as (country), United Kingdom (state) England.

CityName should be set to allow duplicates and then the StateID in the CityT table will correctly populate the city combo box after you select the state in the state combo box. In Richard's table, for CityName, Indexed is set to No.

I thought he used a multi-field index, including CityName and StateID, with duplicates set to NO.  Maybe I am remembering wrong.