We have tried this answer its all working good for customer edit form, but now the issue is,
we have used magestore onestepcheckout,
also we have added
<li>
<div class="one-field">
<input onkeyup="validateElement(this.id)" type="text"
title="<?php echo Mage::helper('core')->quoteEscape($this->__('Govt ID')) ?>"
name="billing[govt_id]" id="billing:govt_id"
value="380051"
class="input-text"
required/>
<span class="highlight"></span>
<span class="bar"></span>
<label class="required" for="billing:govt_id"><?php echo $this->__('Govt ID') ?> <em>*</em></label>
</div>
</li>
also, we have added,
'govt_id' => Mage::helper('onestepcheckout')->__('Govt Id'),
in the position.php
page
but, know while time of billing value of this newly added govt_id
is not being saved.
For add new address field, you need to create a new extension.
Here, Step-by-step guide for add
Govt Id
in customer address: http://excellencemagentoblog.com/blog/2011/11/29/magento-adding-custom-field-to-customer-address/Hope it helps you:)