Unless you can set me straight here..
The problem with containers, and the prime reason I still haven't found a use for them, is that they can only be bound to one sprite, AND they can't be bound to a family.
So I've got 50 different enemies, I'd have to create 50 unique collider objects and associate each.
That's a bit of a design time nightmare and also uses way more memory than needed, so for now I'm going with what Whiteclaws suggested. Creating and pinning a "larger" collider sprite to a created family enemy at runtime.
Then when the fade of my enemy completes I loop around all colliders, match faded Enemy UID to ParentID (instance variable I manage), and destroy the collider.
If you have a more elegant approach using containers and I'm being silly and missing something, let me know!
As for my request..
I think if you had many masks you'd be able to check for collision to "any" mask which would be the default and look the same as the events look today.
I think you'd additionally be able to check collision against a specific mask per sprite (just like you can reference the sprite's various animations by animation name).