I am designing many child themes for my multisite.
All my child themes will have exactly the same template files with same code and the same functions.php with the same code. They will also share some basic css.
Because the child themes share many of the same things, if I ever get php errors or want to add things I have to go to each child theme to make changes. Also I am continuously going to add my own short-code emoticons so I will continuously be adding them which also means I have to keep going to all my child themes to add them.
Is it possible to create a directory in my themes folder called main and then add a functions.php, add php templates that I will be editing, and a main css file in there where I can have them load first.
So in every child theme functions.php it will 'only' have:
<?php include '../main/functions.php'; ?>
All my child theme template php files, for example, the header.php file will 'only' have:
<?php include '../main/header.php'; ?>
Then the css file in each child theme, I will add at the top of all my css code (for the main css changes):
So the main directory acts as the default, so I can add all my code to the files in the main directory and that way if I get errors, or I want to add things I only have to go to this main directory to make changes, then it will affect all my child themes.
What are your thoughts on this system, I'm not good with php so will this have any affect on my website performance and is it secure, can it have any other problems?