Apologies for my lack of explanation
I want to have 2 select fields. The one on the left is supposed to have parent categories and the one on the right child categories. Just as in the URL I posted.
The thing is, I want the user to be able to add/modify/delete parent and child categories from text fields and buttons. I am attaching a sample image so that everyone can get an idea.
I know it is too much to ask. I've done that in the past pulling categories from databases but never with variables ;(