Some searching didn't uncover an answer to this question, so here I am. I'd be grateful for a smidge of your time.
In short: I'm making some modifications to the template files for the theme I'm using (the theme in this case being Sandbox, but that doesn't matter), and I'm trying to figure out how best to preserve those changes so that when I upgrade to a new version of the theme, I don't have to re-apply everything manually.
It appears that my-hacks.php is *not* relevant here, as that file is only used for preserving changes to WordPress' core files when upgrading to a new version of WordPress itself. Is that right?
A few random examples of the theme mods I'm referring to:
1) Capitalization stuff on buttons.
2) Making certain boilerplate text more personal (eg, in the 404 file).
3) The addition of scripts needed to talk to external services (eg, Google Analytics). I'm obviously not counting stuff that's inserted by plugins, since the plugin typically continues to work after a theme upgrade.
Again, suggestions would be much appreciated. Thanks! :)