Arras WordPress Theme

I've posted about this before but gotten no response.

I want to override filters.php (specifically parts of function arras_postheader) but making a child filters.php does not work, even if I keep the same file structure (library/filters.php).

How can I override the function without changing the parent Arras theme? And yes, I've tried the guide by extatix, which only gave me errors.

Here is what I need to change: Lines 37-39

if ( arras_get_option('post_author') ) {
			$postheader .= sprintf( __('<div class="entry-author">By %s</div>', 'arras'), '<address class="author vcard"><a class="url fn n" href="' . get_author_posts_url( get_the_author_meta('ID') ) . '" title="' . esc_attr(get_the_author()) . '">' . get_the_author() . '</a></address>' );
		}

to:

if ( arras_get_option('post_author') ) {
			if ( function_exists( 'coauthors_posts_links' )) {
			$postheader .= sprintf( __('<div class="entry-author">By %s</div>', 'arras'), '<address class="author vcard"><a class="url fn n" href="' . get_author_posts_url( get_the_author_meta('ID') ) . '" title="' . esc_attr(get_the_author()) . '">' . coauthors_posts_links( null, null, null, null, false ) . '</a></address>' );
			} else {
			$postheader .= sprintf( __('<div class="entry-author">By %s</div>', 'arras'), '<address class="author vcard"><a class="url fn n" href="' . get_author_posts_url( get_the_author_meta('ID') ) . '" title="' . esc_attr(get_the_author()) . '">' . get_the_author() . '</a></address>' );
		}}

Thanks!

To clarify: Directly editing Arras filters.php works, but I want to keep changes in the child theme, as you should.

See: http://wordpress.org/support/topic/integrate-template-tags-into-arras-theme?replies=7


ARRAS VERSION: 1.5.1.2