dofacshs
A goofy module that allows showing one hierarchical vocabulary in the selection form widget and in the display formatter while linking the displayed value to the entity reference filtering links of a separate non-hierarchical vocabulary that the hierarchical vocabulary is connected to by reference fields on its terms.
Currently existing as a proof of concept with hard-coded field names:
field_filter_locationfield_alternate_name_if_parent
With that latter a good idea for the field the on taxonomy terms which will replace the label if this field is filled in and the term is serving as a parent.
This alternate label can be used to hide a parent level of the hierarchy by being set to the text "<hide>"
The former field machine name really has to be made configurable for this module to be useful. If you want it, please file an issue https://www.drupal.org/project/issues/dofacshs?categories=All