Inclusive checkbox list (Automatically checking boxes below selected box)

Inclusive checkbox list (Automatically checking boxes below selected box)

I am making a form where there is a list of permissions available to the
user. Each permission is a checkbox. (Therefore, there is a list of
checkboxes!)
The permissions are inclusive... The top element of the list gives access
to itself as well as the ones below it.
I am trying to model this using the forms UI. I would like the checkboxes
below a checked box to automatically check themselves when a box is
checked above them.