Insert 'select all' choice in a particular level in Taxonomy Term Reference Tree Widget I'm using D7. And I have a big term reference tree with Term Reference Tree. There are so many terms in the tree that I'd like to put 'select all' choice in it for usability.
Is it possible to put 'select all' choice in some level?

Let me show you the example of what I want to do below...

(Ex)
Let's say there is a vocabulary whose name is 'Food'

[Food]
-Vegetable
--Select All
--Pumpkin
--Carrot
--Radish
--Potato
-Fruit
-Fish

So, what I want to do is...if you check the 'Select All' under the Vegetable level, the all of choices(Pumpkin, Carrot, Radish, Potato) will be checked.

I searched the way to do that but couldn't find the answer. Any tips would be appreciated. Thank you.

Added:
I found you can do something like I want to do by the setting below...
-Start minimized =>Whichever
-Leaves only =>Off
-Select parents automatically =>On
-Cascading selection =>On

With the setting above, you can chose all choices by checking the parent level.
But, I also wanted to enforce users to chose the deepest level.
With the setting above, users don't always have to chose the deepest level...
So, correctly, I'd like to say I want to put 'select all' and enforce users chose the deepest level.
I still need your help. Thank you.
Drupal have Taxonomy Manager module where all levels and terms have checkbox options and also add, edit, delete, move, functionality here.
Taxonomy Manager:

This module provides a powerful interface for managing taxonomies. A vocabulary gets displayed in a dynamic tree view, where parent terms can be expanded to list their nested child terms or can be collapsed.
For using the Taxonomy Manager you should have JavaScript and automatically load of images enabled in your browser.