Adding services after container has been built

Since ContainerBuilder.Update has been deprecated, the new recommendation is to use child lifetime scope.

Adding Registrations to a Lifetime Scope

Autofac allows you to add registrations “on the fly” as you create lifetime scopes. This can help you when you need to do a sort of “spot weld” limited registration override or if you generally just need some additional stuff in a scope that you don’t want to register globally. You do this by passing a lambda to BeginLifetimeScope() that takes a ContainerBuilder and adds registrations.

using(var scope = container.BeginLifetimeScope(
  builder =>
  {
    builder.RegisterType<Override>().As<IService>();
    builder.RegisterModule<MyModule>();
  }))
{
  // The additional registrations will be available
  // only in this lifetime scope.
}

Working with Lifetime Scopes

Yes you can, using the Update method on ContainerBuilder:

var newBuilder = new ContainerBuilder();
newBuilder.Register...;

newBuilder.Update(existingContainer);