That's fine, so you make the condition Paris is occupied or not a war with France.You are both right and wrong at the same time.
The main problem with National Focuses is that AI will use them once it has them and can enforce them, regardless of its strategical situation. Limiting their use in some way might be seen as the way out, but at the same time Germany, for example, should be able to declare war on Soviet Union if Paris is part of the Axis.