Navigation link portfolios within category

Dear friends,

I put on my portfolios wordpress the widget Navigation links, but I want Navigation link portfolios within category.

For example, I have 2 categories A and B, I want category B navigation link not to connect to category A

This is code in /

wp-content/plugins/designthemes-portfolio-addon/functions-singlepage.php


if($type == 'type2') {

$output .= '<div class="post-nav-container '.$type.'">';
$output .= '<div class="post-prev-link">';
$output .= get_previous_post_link('%link', '<i class="icomoon icon-Arrow-OutLeft"> </i>' );
$output .= '</div>';
$output .= '<div class="post-archive-link-wrapper">';
$output .= '<a class="post-archive-link" href="'.get_post_type_archive_link('dt_portfolios').'"></a>';
$output .= '</div>';
$output .= '<div class="post-next-link">';
$output .= get_next_post_link('%link', '<i class="icomoon icon-Arrow-OutRight"> </i>');
$output .= '</div>';
$output .= '</div>';

}

what can I modify it?