You can link your Jerarquia_pais2 hierarchybelongsto table with another table created with the hierarchy function. See the Treebridge and Trees table in the attached example. The Trees table contains a Treepath field that is used in a listbox to select a district. In the pivot table this district and the underlying districts are shown.
Note, there's also a way to select entire subtrees without a hierarchybelongsto table. First collapse the parent of the subtree you want to select and then select the parent node of that subtree. If you then expand it you'll see that the nodes below it are also selected. If you expand the node first and then select it only the node itself will be selected.