Select2 - hide/show optgoup based on another selection?

[j inch]

I am trying to get two select2 dropdowns to respond to each other based on state /country selection.

i.e. if United States is selected show only the "optgroup" for the states in the other drop down / if Canada is selected - only show provinces / if any other is selected disable and remove required attribute.

So far I found this code that I am trying to implement in my select2 setup but unfortunately I am having no luck.

It seams to not recognize the hide/show script for the select2 "optgroup"? This work if not using a select2 setup so not sure how I can work around.

Any advise is welcome.

Demo on jsfiddle