This module will provide a field type to manage hierarchical dependency between related Drupal 8 entities.
For now, it only works between content types but we have plans to support taxonomy vocabularies and bock types in near future.
How to use:
Go to Manage Fields on any content type and then press on Add field.
Now select the Dependency field type.
Once created, go to Manage form display, make sure that you have selected the Dependency select widget and in its settings, you must specify the entities to display on the field.