John P. Bloch

Create child themes from any non-child theme with the click of a button.
This plugin is multisite compatible; if used on a multisite network, controls for creating child themes will be in the network admin instead of the regular site admin. Pick the parent theme from the dropdown and name name your new child theme. You can also change the author name and select files you want to copy from the parent to the new theme.
Click the button and you’re all set!

Child Themify

Create child themes with the click of a button.

alekc

Sometimes you don’t want to show parent directories in permalink because they are not really necessary or because you know that in the future your child directory will change it’s parent.
For example: 
+Work in progress 
–Site 1 
–Site 2 
+Work Finished 
–Site 3
In this case Site 3 originally have been part of “Work in progress”, and on job done it has been moved under “Work Finished”.
So if you install this plugin your link will be transformed in this way:
domain.com/parent_category/child_directory/post_name => domain.com/child_directory/post_name 
domain.com/category/parent_category => domain.com/parent_category 
domain.com/category/parent_category/child_directory => domain.com/parent_category/child_directory

Remove Parents

Remove Parents is a tiny plugin which remove "category" and parent categories from permalink.

Child Themify vs Remove Parents