Inscription types: add "admin only" to closed,and open

We have instances which are for a specific audiance: only those who belong to a community / NGO should be able to create accounts.

For now we have only two ways to manage inscriptions: either they are completely closed or anybody can join.

Please add a new inscription management possibility where only admins could add new users.

Here is how it could be implemented:

Inscriptions are either: -closed - nobody can create an account -open - everybody can create an account -managed by admin - only instance admin can create new accounts

With the option "managed by admin", the button "join" (s'enregistrer) should not be displayed on the main page, but should be added in the admin menu. Then the admin could create the account and send it to the user with a to-be-changed password:

This or any way to manage an instance decidated to a specific community would be much welcome.