Hierarchy Node Question

Hello, is it possible to default the parent nod of a hierarchy in variable screen.  For example.  I have 0Material which has a hierarchy built and it goes like this:

Parent

- Child 1

  - - Child1's child

- Child 2

- - Child2's child

and so on.  Now, I want to create a hierarchy node variable which is possible but when ever it comes up on the screen, i want the main parent node always populated in it by default like 'PARENT'. is there a way to make it happen?

Thanks.