<odoo>

    <template
        id="pms_proforma_invoice_template"
        name="Invoice Proforma Portal Template"
        inherit_id="account.portal_invoice_page"
        priority="20"
        primary="True"
    >
        <xpath expr="//iframe[@id='invoice_html']" position="attributes">
            <attribute
                name="t-att-src"
            >invoice.get_proforma_portal_url(report_type='html')</attribute>
        </xpath>
    </template>

</odoo>
