Really? I think even with the hierarchy structure people would have lists like this:
- Biology
- To Do
- Read textbook
- Solve problems
- X
- Notes
- Charles Darwin wrote The Origin of Species.
- Gregor Mendal wrote Experiments on Plant Hybridization.
- To Do
In this case, when you insert an item at X, it should be a checklist. Thus, it shouldn’t inherit properties from the parent but rather from the previous item.