Products
$tax_query = array( 'relation' => 'AND', array( 'taxonomy' => 'Products', 'field' => 'term_id', 'operator' => 'EXISTS', 'include_children' => true, ), array( 'taxonomy' => 'Articles', 'field' => 'term_id', 'operator' => 'EXISTS', 'include_children' => true, ), );