I'm trying to build blocks, page types, etc with defaults and/or hard-coded PHP so that others can easily create course modules with task assignments like this:

Home
Module 1
Task 1
Task 2
Module 2
Task 1
Task 2
Task 3
...

Included "for free" should be sidebars showing a module's subtasks.
By editing the defaults for the module page type, I have a pagelist sidebar for the module subtasks. For the task page type, I had to create a default pagelist collecting all tasks for all modules and a custom template filtering out non-siblings. Is there a better way? I tried all the auto-nav options, including level above + display all subpages, and never got the tasks, just the pages above.