How can we add a block only for a certain subcategory only so that the content is displayed for that subcategory and not all categories or its parent categories as well ?
create a block turn it off then make it appear for only the categories you need.
http://forum.cs-cart.com/topic/29473-create-block-and-then-disable-it-for-the-rest-of-categories/
Great it works for us...