Taxonomies relations

Much like your search question….relation in what way? You could have a post type of “recording artist” and taxonomies of “music genre” and “music format” and they’d be implicitly related at minimum, but not necessarily explicitly where the site behaves different depending on genre an format values.

Also a detail we don’t have any specific settings for.

Realation like a parent. For example, in this case: https://ibb.co/strVW29
On the left are “country” and on the rigth are “cities”. I can create a parent between us.

As you can see, that’s absolutely possible with terms within a single taxonomy. However, I don’t know of any great way to tie taxonomies themselves together with each other.

Ah ok. No problem.