By popular request there follows the definitive guide to setting up a child theme to use with the Mingle theme.

1. Give the child a name

Inside the wp-content/themes/ folder create a new folder named eskarina.

2. Give the child some style

Create a file inside the eskarina folder named style.css with the following content:

/*  
Theme Name: Eskarina
Description: Child of the Mingle theme
Author: Terry Pratchett
Template: parallelus-mingle
Tags: buddypress
*/
@import url("../parallelus-mingle/style.css");

Then create seven more css files:

style-default.css
style-skin-1.css
style-skin-2.css
style-skin-3.css
style-skin-4.css
style-skin-5.css
style-skin-6.css

The content of the style-default.css is just the one line, as follows:

@import url("../parallelus-mingle/style-default.css");

The content of the style-skin-1.css file is four lines, as follows:

/*
	Skin Name: Skin 1
*/
@import url("../parallelus-mingle/style-skin-1.css");

The content of the other five skin files is similar to the style-skin-1.css file above, except that you change according to the skin number the Skin Name on line 2 and the file name of the imported file on line 4.

3. Give the child some assets

Copy the entire assets folder from the parallelus-mingle folder into the eskarina folder.

4. A child is born

Go to Appearance > Themes and activate the Eskarina theme.

Go to Appearance > Menus > Theme Locations and make sure the Main Menu – Left and Main Menu – Right options are set to the correct menus.

From now on you can make any style additions or alterations to the relevant skin css file in Eskarina, but remember that the @import must be the first css in the file, there must be nothing before the @import except comments.

Other things you can do with a child theme include making your own functions.php file that could contain (for example) additional shortcodes, custom post types or custom taxonomies.

If you wanted to mess with a Mingle template, let’s say the template-page.php file that determines how pages are displayed, then you would copy template-page.php from parallelus-mingle into eskarina and then you would make whatever changes you wanted to the eskarina/template-page.php file, leaving the original Mingle template untouched.  

Resources

• WordPress child theme documentation: http://codex.wordpress.org/Child_Themes