How to make a submenu in the admin panel?

Question

Django

New to django.
I have three applications: Clients, Stores, Warehouse

Now I need to make a submenu. For example, if you enter the "Clients" application above breadcrumbs (for example), display links: Wholesale, Individuals. Do the same for other applications
Where to write the condition that there is this application "Client" to show such and such a menu.
And yet - also how to hide it from certain users?
Thank you!

Answer 1

Admin panel for a simple
Admin panel not for clients
Admin panel only for trusted
ones If you want to change the admin panel - use a separate app - it will be easier

Answer 2

Read carefully, there are a lot of useful things on this topic: djbook.ru/rel1.8/ref/contrib/admin/index.html
In short, you need to partially rewrite the admin templates + add JavaScript code. I think this gave a direction where to dig.