Handle IoC configuration with shared dependencies between projects

I've a root project (root), some modules (A, B), and these modules have some external dependencies (Z). I'm using an IoC container.

I'm using C# here, but is a generic pattern question. Let say that my container is services, and I can initialize IoC configuration with use of extension methods. So in root project I'm writing:

services.AddModuleA();
services.AddModuleB();

On module A I've this method:

public static void AddModuleA(this IServiceCollection services)
{
    // Init module internal services.
    //services.AddScoped<IA1Service, A1Service>();
    //...

    // Init module external dependencies.
    services.AddDependencyZ();
}

On module B I've a similar method:

public static void AddModuleB(this IServiceCollection services)
{
    // Init module internal services.
    //...

    // Init module external dependencies.
    services.AddDependencyZ();
}

Obviously Z dependency was already been added, so this tells me that I should not configure it inside a module extension method, and I should rather declare its configuration in root project:

services.AddModuleA();
services.AddModuleB();
services.AddDependencyZ();

But doesn't this break the Least Knowledge principle? Importing and configuring a module A (or B) will bring to a cascade explicit declaration of all dependency configurations.

And related question, is declaring the extension methods AddModuleA() and AddModuleB() a bad pattern at all? Could be a better idea to configure directly on root only services that I will use? And in this case (a bit extreme), what about config of internal use only class?