Migrate Theme Customizations (Theme Mods) from Parent to Child.

child_migrate_theme_mods.php

<?php

/**
 * Migrate Theme Customizations (Theme Mods) from Parent to Child.
 *
 * WordPress stores Customizer settings separately for each theme based on folder name.
 * When switching to a child theme, settings seem to reset. This function automatically
 * copies those settings from the parent theme 'hello-shoppable' exactly once.
 */
function hello_shoppable_child_migrate_theme_mods() {
	if ( ! get_option( 'hello_shoppable_child_mods_migrated' ) ) {
		$parent_mods = get_option( 'theme_mods_hello-shoppable' );
		if ( ! empty( $parent_mods ) ) {
			foreach ( $parent_mods as $key => $value ) {
				set_theme_mod( $key, $value );
			}
		}
		// Set option flag to prevent re-running on subsequent page loads
		update_option( 'hello_shoppable_child_mods_migrated', true );
	}
}
add_action( 'after_setup_theme', 'hello_shoppable_child_migrate_theme_mods' );