Plugin create pages and use templates

I got it. It kind of makes sense but doesnt really. The one template wasnt working becuase I was looking for just the slug. Since its a child of the other page I needed to add it in the is_page statement. This worked (I also just did it all in one function):

function ch_register_page_template($page_template;) {////////////////<-------------Works

    if ( is_page( 'CH' ) ) { //change this to match slug
        $page_template = dirname( __FILE__ ) . '/inc/page-ch.php';
        return $page_template;
    }

    if ( is_page( 'CH/CH-Thank-you' ) ) {//change this to match slug
        $page_template = dirname( __FILE__ ) . '/inc/page-ch-thank-you.php';
        return $page_template;

    }

    return $page_template;

}

add_filter( 'page_template', 'ch_register_page_template' );