Magento 1.7 XML Layout – How to Add Admin Page New Menu and Sub Menu

I tried to create a simple module and menu.The Menu is successfully created and show.
My question is how to add the same menu as a sub menu of existing menus(Ex : System).

here is my Approach to achieve this.

My config.mxl file – Path(app\code\local\Muja\Hidh\etc)

<?xml version="1.0"?>
<config>
<modules>
<Muja_Hidh>
  <version>0.1.0</version>
</Muja_Hidh>
</modules>
<frontend>
<routers>
<hidh>
    <use>standard</use>
      <args>
        <module>Muja_Hidh</module>
        <frontName>hidh</frontName>
      </args>
  </hidh>
</routers>
</frontend>
<global>
<helpers>
  <hidh>
    <class>Muja_Hidh_Helper</class>
  </hidh>
</helpers>
<blocks>
  <hidh>
    <class>Muja_Hidh_Block</class>
  </hidh>
</blocks>
<models>
  <hidh>
    <class>Muja_Hidh_Model</class>
    <resourceModel>hidh_mysql4</resourceModel>
  </hidh>
</models>
<resources>
<hidh_setup>
    <setup>
      <module>Muja_Hidh</module>
    </setup>
    <connection>
      <use>core_setup</use>
    </connection>
  </hidh_setup>
  <hidh_write>
    <connection>
      <use>core_write</use>
    </connection>
  </hidh_write>
  <hidh_read>
    <connection>
      <use>core_read</use>
    </connection>
  </hidh_read>
</resources>
</global>
<admin>
<routers>
  <hidh>
    <use>admin</use>
    <args>
      <module>Muja_Hidh</module>
      <frontName>admin_pets</frontName>
    </args>
  </hidh>
</routers>
</admin>
<adminhtml>
<menu>
  <hidh module="hidh">
    <title>My Pets</title>
    <sort_order>100</sort_order>
    <children>
      <hidhbackend module="hidh">
        <title>Pet List</title>
        <sort_order>0</sort_order>
        <action>admin_hidh/adminhtml_hidhbackend </action>
      </hidhbackend>
    </children>
  </hidh>
</menu>
<acl>
  <resources>
    <all>
      <title>Allow Everything</title>
    </all>
    <admin>
      <children>
        <hidh translate="title" module="hidh">
          <title>Hidh</title>
          <sort_order>1000</sort_order>
          <children>
      <hidhbackend translate="title">
        <title>Muja Kuja</title>
      </hidhbackend>
          </children>
        </hidh>
      </children>
    </admin>
</resources>
</acl>
</adminhtml>
</config>

My Layout.xml was Muja_Hidh.xml : Path(app\etc\modules)

<?xml version="1.0" encoding="utf-8"?>
<config>
<modules>
    <Muja_Hidh>
        <active>true</active>
        <codePool>local</codePool>
    </Muja_Hidh>
</modules>

I can view the menu after system main menu.My question is how can i add it into under System menu.