[keycloak-user] Multi-country domain

Hello, We need to develop a domain with multiple countries and one admin per country. Those admin users can only see, edit and create users that belong to its country. I don't know if the best approach to set a country to a user is as an attribute or creating one group per country. I would like to know what would be the best approach to solve this and if it's possible to restrict one admin user to manage only it's country users. Thank you, Raul