Topic: Nested items
Have you/could you consider the concept of nested to-dos? I'm thinking only one sub-level.
On the included screen shot, I have 3 to-dos each of which have one or more sub-tasks.
The main to-do can be marked as complete, but not the sub-tasks.
My thought is that I could show sub-tasks as visibly indented and then check at the sub-task or main to-do level.
If I check all sub-tasks, then the main to-do is checked for me, or if I check the to-do, all the sub-tasks are checked.
Hope this makes sense.