Startup.cs

public IServiceProvider ConfigureServices(IServiceCollection services)
{
  services.AddXXX()
  ....
  services.AddMultiTenancy<AppTenant>((multiTenancyOptions) =>
            {
                multiTenancyOptions
                    .DistinguishTenantsWith<HeaderTenantDistinguisherFactory>()
                    .InitialiseTenant<TenantShellFactory>()
                    .ConfigureTenantContainers((containerBuilder) =>
                    {
                        containerBuilder.WithStructureMap((tenant, tenantServices) =>
                        {
                            //add a bunch of tenant services
                        });
                    });
            });
 
   var container = new Container();
            
   container.Configure(config =>
   {
       config.Populate(services);
       // add generic services
   });

   return container.GetInstance<IServiceProvider>();
}