Thanks for the answer @james
Unfortunately, this doesn’t solve my problem, because countries and cities was just head of the tree, there’s also should be possibility to assign address to city, then date to address etc. Quite a big a tree.
I reconsider my first question, and, sorry, I did a mistake in it. So, the country should be like post, and then, in that post, custom fields with cities, addresses, dates as values. Then, it should be possibility to make endless quantity of values (repeater, I know), and possibility to assign (or make relationship) address(es) to specific city. Then – date(s) to address. So, city should have many addresses, and after that, address should have many dates.
Custom post types can’t help here, imo, because it’ll be too complicated for user.
