Is it possible to create logic that, when selecting a parent category, only the child categories are filtered in the select list? For example: the parent category "continent" includes 3 items: Europe, America, Asia. Create a child category "country" of the parent category "continent" : including the countries of England, France, Germany, America, Canada, China, Japan, Korea. Each of these countries is a subcategory of "country" and has subcategory relationship logic added to the "continent" category. Create new post (blog) with parent categories and child categories, when selecting the parent category - America, the child category only shows 2 options: United States and Canada (Asian and European countries are not displayed for selection) I think this gives 200% power to blog, product category, related posts filter,....