SAT roster

// Add students to roster upon registration 
add_action('gform_after_submission_2', 'update_sat_roster', 10, 2);
function update_sat_roster($entry, $form) {
    //getting post and entry data
    if($entry["26"]) : 
      $post_num = $entry["26"];
    else : 
    	$post_num = $entry["18"]; 
    endif;
    $taken = get_post_meta($post_num, 'seats_taken' , true);
	$new_taken = $taken + 1; 
    //update roster
	update_post_meta($post_num, 'seats_taken', $new_taken);
	update_post_meta($post_num, 'roster_'.$taken.'_first_name' , $entry["2.3"]); 
	update_post_meta($post_num, 'roster_'.$taken.'_last_name' , $entry["2.6"]); 
	update_post_meta($post_num, 'roster_'.$taken.'_school' , $entry["6"]); 
	update_post_meta($post_num, 'roster_'.$taken.'_email' , $entry["9"]); 
	update_post_meta($post_num, 'roster_'.$taken.'_phone' , $entry["5"]); 
}