Using the Migrate API and the explode and entity generate plugins from Migrate Plus, I was able to bring in a couple thousand taxonomy terms. They were listed in the source as:
They all came over ok, but as a flat hierarchy. Now I need to bulk manage them to manually (but quickly) create their parent child relationships.
This seems to have been the job of the Taxonomy Manager module for D7 and before, but, as it even states in the description, D8 version is missing a lot of functionality.
Preferably, I could bulk select several terms and associate them all at once to their parent.
Thoughts on how to achieve this through the UI in D8?