"custom_sale_order_template" model=" mail.template">
        "name">My Custom Template
        "subject">Sale Order <!--(#${object.source_sale_id.name})-->< /span>
        "model_id" ref="sale.model_sale_orde"/ >

        "partner_to">{{ object.partner_id.id }}
        "reply_to">{{user.email_formatted}}
        "report_template" ref="sale.action_report_saleorder"/ >
        "report_name">Sale Order
        "lang">{{ object.partner_id.lang }}
        "auto_delete" eval="True"/>
        "body_html" type="html">
            
"html_body"/>
        
    


inside the field name=body html, i want to insert a html file template and reuse it by changing some 
 parts only in the separate html file. is that possible?