Show/Hide rows

I have searched the archives here, but not found what I'm looking for.
I am working on a CPM (Critical Path Management) project.

The sheet will consist of many tasks and many more subtasks. I would like to be able to show/hide the subtasks at will just as in Windows Explorer.
I would also need to be able to add and delete both tasks and subtasks and still have it work.
Ideally, it would have the plus/minus sign that everyone is used to at each main task.
I have looked at Data Groups but I think that will be too confusing for some of the users.

Column A is where I would put this. I could change the format in the ID column if that would make a difference.

Thanks,

Len Silva

I feel like someone must have already done this as it would be a very useful app, but I haven't found it.cpmtest.xlsm