diff --git a/app/assets/javascripts/nested_setting.js b/app/assets/javascripts/nested_setting.js
index ad94241..ef837fb 100644
--- a/app/assets/javascripts/nested_setting.js
+++ b/app/assets/javascripts/nested_setting.js
@@ -2,6 +2,25 @@
   "use strict";
 
   $(function(){
+    if($('.nested-column.multiple').length === 0) return;
+
+    var $setting = $('.nested-column.multiple:first');
+    var counter = 0;
+
+    $('.append', $setting).on('click', function(ev){
+      ev.preventDefault();
+      var $new = $setting.clone(true);
+      var elements = $('.form-control', $new);
+      _.each(elements, function(elm){
+        elm.name = elm.name.replace("0", ++counter);
+      });
+      var $close = $(this).clone().text('-');
+      $close.on('click', function(){
+        $new.remove();
+      });
+      $(".append", $new).replaceWith($close);
+      $new.appendTo($setting.parent());
+    });
   });
 })();
 
diff --git a/app/helpers/settings_helper.rb b/app/helpers/settings_helper.rb
index 773f558..5acca10 100644
--- a/app/helpers/settings_helper.rb
+++ b/app/helpers/settings_helper.rb
@@ -17,14 +17,19 @@ module SettingsHelper
       html << h(form.label(key))
       child_data = form.object.class.children[key]
       klass = child_data[:class]
+      options = child_data[:options]
       children = form.object.send(key) || {"0" => {}}
       children.each_pair do |index, child|
-        # TODO: allow append/delete for multiple child
-        form.fields_for("#{key}[#{index}]", klass.new(child), class: "nested-column #{child_data[:multiple] ? "multiple" : ""} well well-sm") do |ff|
+        html << %Q!<div class="nested-column #{options[:multiple] ? "multiple" : ""} well well-sm">!
+        if options[:multiple]
+          html << %Q!<a class="btn btn-default append">+</a>!
+        end
+        form.fields_for("#{key}[#{index}]", klass.new(child)) do |ff|
           klass::KEYS.each do |k|
             html << field(ff, k)
           end
         end
+        html << "</div>"
       end
     else
       html << h(form.label(key))
diff --git a/app/models/fluentd/setting/common.rb b/app/models/fluentd/setting/common.rb
index d1f883f..976b749 100644
--- a/app/models/fluentd/setting/common.rb
+++ b/app/models/fluentd/setting/common.rb
@@ -57,6 +57,18 @@ class Fluentd
         end
       end
 
+      def children_of(key)
+        meta = self.class.children[key]
+        return unless meta
+        klass = meta[:class]
+        data = send(key) || {"0" => {}}
+        children = []
+        data.each_pair do |index, attrs|
+          children << klass.new(attrs)
+        end
+        children
+      end
+
       def child_class(key)
         self.class.children[key][:class]
       end
diff --git a/app/models/fluentd/setting/out_forward.rb b/app/models/fluentd/setting/out_forward.rb
index 75605df..2c56350 100644
--- a/app/models/fluentd/setting/out_forward.rb
+++ b/app/models/fluentd/setting/out_forward.rb
@@ -12,12 +12,13 @@ class Fluentd
         flags :standby
 
         validates :host, presence: true
+        validates :port, presence: true
       end
 
       class Secondary
         include Common
         KEYS = [
-          :path, :type
+          :type, :path
         ].freeze
 
         attr_accessor(*KEYS)
@@ -37,24 +38,32 @@ class Fluentd
 
       attr_accessor(*KEYS)
       choice :heartbeat_type, %w(udp tcp)
-      nested :server, Server
+      nested :server, Server, multiple: true
       nested :secondary, Secondary
 
       validates :match, presence: true
-      validate :validate_at_least_one_server
+      validate :validate_has_at_least_one_server
       validate :validate_nested_values
 
-      def validate_at_least_one_server
-        # FIXME: real validation
-        true
+      def validate_has_at_least_one_server
+        if children_of(:server).reject{|s| s.empty_value? }.blank?
+          errors.add(:base, :out_forward_blank_server)
+        end
       end
 
       def validate_nested_values
-        # FIXME: real validation with child class instance
-        self.class.children.inject(true) do |result, child|
-          # result & child.valid?
+        self.class.children.inject(true) do |result, (key, _)|
+          children_of(key).each do |child|
+            if !child.empty_value? && !child.valid?
+              child.errors.full_messages.each do |message|
+                errors.add(:base, "(#{key})#{message}")
+              end
+              result = false
+            end
+            result
+          end
+          result
         end
-        true
       end
     end
   end
diff --git a/config/locales/translation_en.yml b/config/locales/translation_en.yml
index ae72251..c8281b5 100644
--- a/config/locales/translation_en.yml
+++ b/config/locales/translation_en.yml
@@ -373,6 +373,7 @@ en:
       lack_write_permission: doesn't writable
       is_a_directory: is a directory. should be a file
       duplicated_conf: Configurations is duplicated
+      out_forward_blank_server: server settings should be at least one
 
   activemodel: &activemodel
     errors:
diff --git a/config/locales/translation_ja.yml b/config/locales/translation_ja.yml
index 0e3dc1f..8b5a347 100644
--- a/config/locales/translation_ja.yml
+++ b/config/locales/translation_ja.yml
@@ -370,6 +370,7 @@ ja:
       lack_write_permission: の書き込み権限がありません
       is_a_directory: はディレクトリです。ファイルを指定してください
       duplicated_conf: 同じ内容の設定がすでに存在しています
+      out_forward_blank_server: serverの設定がありません。
 
   activemodel: &activemodel
     errors: