If you intend to make any modifications to the theme files it is strongly recommended that you create a child theme as then your modifications will not be overwritten if you upgrade the main theme. A minimal child theme simply contains a
style.css stylesheet that makes the theme visible to WordPress, tells it the name of its parent, and then typically pulls in the parent stylesheet. If you are not familiar with child themes it is probably worth having a quick read of the WordPress primer about them.
Any template files that you add to your child theme will override the similarly named file in the parent theme so if you want to tweak them you can copy a file over and then make the edits. You can also add template files that the parent theme doesn't have. The exception to this is
functions.php file where the child file is processed in addition to the parent one (specifically, it is processed before the parent file).
The Scouting Challenge theme should work be able to work correctly with child themes, and if it doesn't then that is a bug that will be fixed. There was a potential incompatibility in that
functions.php was not written to allow for any conflicting definitions in the child theme but that was pretty unlikely to start with and is corrected in 3.4.1. All the
*-options.php files are capable of being overridden by the child theme, not just the WordPress built-in templates.
In order to get you going a minimal child theme has been created which has been named Scouting Challenge Plus (previously Beverley Hall Annex). This should be installed after you have installed the main theme.
Version 2.0.0 of Scouting Challenge Plus is available for download now.
This is a zip file and should be uploaded to WordPress in exactly the same fashion as the main Scouting Challenge theme (Appearance > Themes > Add New > Upload Theme and then follow the instructions).
Once the theme is installed in WordPress you can activate it. You might like to change the name of the theme to something of your own choosing. You do that by editing the
style.css file. It should be pretty self-evident what goes where, especially if you've read the primer mentioned previously. There is no need to rename the child theme folder but you can if you wish. Keep the folder name simple as it will be part of a URL (stick to letters, digits, hyphens and underscores and don't use spaces).
When you are using a child theme a line is added to the theme footer to maintain a credit for the Scouting Challenge theme (you can see that at the bottom of this page).
This site is using the Scouting Challenge Plus child theme. The stylesheet has been tweaked to rename it as the Scouting Challenge Documentation theme and add some minor CSS tweaks, mainly to handle tables inherited from a previous static HTML site. A 'favicon' has been uploaded into the theme where it is automatically detected by the parent theme and used instead of the default fleur-de-lis. That is it. Everything else you see exploits the existing capabilities of the parent Scouting Challenge theme. For example the logo, which replaces the default TSA 'swish' logo, uses the capability in 4.0.3 to use an image that has been uploaded to the Media Library.