I’m using this permalink for all /%category%/%postname%/. Due to some reasons i want to change permalink to /anyword/%post_id%/ for a single category and it’s sub-categories.
i.e. For all - permalink is like this - www.example.com/categoryname/postname
and i want to change permalink for “world” category and it’s subcategories like “india”,“u.s.” etc. to this - www.example.com/world/34343
I don’t want to affect any other permalink structure and permalinsk.
I’ve tried every plugin related to my problem. But no luck with that. 
that’s why i posted here. From some days i’m working on custom post type. And got a little success too. May be i’ll use custom post type instead for changing permalinks for specific category. But if someone can answer it please do.