Forbidden Options Greyed Out Not Hidden

Hi. I have setup some forbidden options for a product. I have "Hide Exception' selected in Settings / General.

I have three drop down boxes with options. I want the second or third to be hidden depending on the selection of the first.

The options are working well but instead of being hidden the drop down box is being greyed out.

Thanks in advance for any help.

Also interested in if there was a way to just hide "out of sight" the forbidden options. Not just greyed out..