Thanks for the response and sorry for not providing the complete details. I want to display the tree view only possible values. The expression i am using is allowing me to get the functionality but it is restricting the usablilty as it is not allowing to select the parent (Which will let all the childrens get selected)
Now i need to each individual child has to be selected.
So i am using this expression to limit the listbox for only possible values
Is there any other way we can create an expression to limit the list box to limit the possible values.