We work on delivering software projects, and when we start a project we create a client folder and create a list. On the list are Deliverable Tasks (with dates) that could have subtasks on them, but they are the high level tasks we want to complete and track in the project.

We also like to work in Sprints, and we like to manually create and manage sprint tasks, maybe called 'Sprint 1', on the same list, with its subtasks on what should be completed in Sprint 1. We would like the ability to link a subtask under 'Sprint 1' to a Deliverable task, and be able to mirror or synchronize the subtask status with the Deliverable task, so when the Sprint 1 subtask status changes as we are working on it, the Deliverable Task changes as well, which allows us to avoid managing duplicate tasks.

A possible implementation of this might sound something like this:

Looking at the dependencies section, where you can link tasks that are 'blocking' or 'waiting on' this task. I think another option here would be very helpful, 'Synchronized' might be the name of the option. So if I create a Deliverable task, a Sprint 1 task, and a subtask under sprint 1 that I want linked to that deliverable task, I can have them 'Synchronized' so when I mark the subtask under Sprint 1 as 'Done', the Deliverable task is also marked as 'Done'