Checklist items with Assigned users and due dates

A task kan have several items at the checklist.
Sometimes you can consider them as a small (sub)task.

And often some of the items (I call them subtasks) must be done by different users.

It should be nice If you can assign a user to a item.
So the subtask wil be seen at the task stream of that user. 
And It would even be greater if the item also has a due date.


The other way to do this is.
An Item in a Task is a connected to an already existing separate Task.
But I think that is more confusing.