TEMPLATEPATH not compatible with child themes

Hi there,
I was trying to override the default single FAQ template in my child theme and was struggling to figure out what was happening. I should be able to place a single-qa_faqs.php into my theme and create a custom template for a single FAQ. This is the way the standard WP templating engine works. See: https://codex.www.ads-software.com/Template_Hierarchy

I found the problem here (line 103 of function.php):

if ( is_single() && 'qa_faqs' == get_post_type($post) ) {

	if ( file_exists( TEMPLATEPATH . '/single-qa_faqs.php') ) {
		$page_template = TEMPLATEPATH . '/single-qa_faqs.php';
	} elseif ( file_exists( TEMPLATEPATH . '/page.php') ) {
		$page_template = TEMPLATEPATH . '/page.php';
	} elseif ( file_exists( TEMPLATEPATH . '/single.php' )) {
		$page_template = TEMPLATEPATH . '/single.php';
	} else {
		$page_template = TEMPLATEPATH . '/index.php';
	}
}

That TEMPLATEPATH constant is only going to work on themes that are parent themes. This is a big problem for anyone using theme frameworks such as Genesis.

https://www.ads-software.com/plugins/q-and-a/