Allow access on children items

I don't think my request is same as http://drupal.org/node/127621, however, this is the scenario:

- I have a fixed hierarchy eg. country/region/city;
- the site will have a lot of user posting content, and some users should only be allowed to post content to eg. region_A AND city_1 or just city_2. That is a user that can post content just to city 2 cannot post content to its parents;
- I have created a role that hasn't got any access to the site vocabularies AND then, for each user belonging to that role, I modify the specific permissions.

TAC LITE does block non-allowed contents, BUT it doesn't dig into hierarchy. So, if user John Doe can only edit city_2, the taxonomy select box in node/add mask remains empty. To let him see his taxonomy item in the select box, I have to grant access on all parent items, which will give the user the unwanted permission to post contents related to the top level.