<template id="portal_my_home_menu_invoice" name="Portal layout : invoice menu entries" inherit_id="portal.portal_breadcrumbs" priority="30">
        <xpath expr="//ol[hasclass('o_portal_submenu')]" position="inside">
            <li t-if="page_name == 'invoice'" t-attf-class="breadcrumb-item #{'active ' if not invoice else ''}">
                <a t-if="invoice" t-attf-href="/my/invoices?{{ keep_query() }}">Invoices &amp; Bills</a>
                <t t-else="">Invoices &amp; Bills</t>
            </li>
            <li t-if="invoice" class="breadcrumb-item active">
                <t t-out="invoice.name" t-if="invoice.name != '/'"/>
                <t t-else=""><em>Draft Invoice</em></t>
            </li>
        </xpath>
    </template>

This is the default template that I have, I want to replace this with my template

 <template id="portal_my_home_menu_inherit" inherit_id="account.portal_my_home_menu_invoice" name="Inherited Invoice Breadcrumb">
        <xpath expr="//ol[hasclass('o_portal_submenu')]/li" position="replace">
            <li t-if="page_name == 'invoice'" class="breadcrumb-item">
                <a href="/my">My Custom Invoices</a>
            </li>
        </xpath>
    </template>

But instead of replacing the default, It gets added inside the breadcrumbs.I check through the source code and example, but most of it refer to adding new values inside the breadcrumbs instead of replacing the existing ones.