Call a phtml file from another phtml on magento 1x. Please follow the bellow steps there are several way you can call phtml files.
When you want to add phtml on same module Then you need to follow this code. Use bellow code on your xml file.
If you want to add a phtml file inside a phtml then follow this code.
echo $this->getLayout()->createBlock('customer/form_edit') ->setTemplate('customer/form/edit.phtml')->toHtml();