contract/agreement_account/views/account_invoice.xml

<?xml version="1.0"?>
<!--
  © 2017 Akretion (Alexis de Lattre <alexis.delattre@akretion.com>)
  License AGPL-3.0 or later (http://www.gnu.org/licenses/agpl).
-->

<odoo>


<record id="invoice_form" model="ir.ui.view">
    <field name="name">sale.agreement.account.invoice.form</field>
    <field name="model">account.invoice</field>
    <field name="inherit_id" ref="account.invoice_form"/>
    <field name="arch" type="xml">
        <xpath expr="//page/group/group/field[@name='name']" position="after">
            <field name="sale_agreement_id"
                domain="[('partner_id', 'child_of', commercial_partner_id)]"
                context="{'default_partner_id': commercial_partner_id}"/>
            <field name="commercial_partner_id" invisible="1"/>
        </xpath>
    </field>
</record>

<record id="view_account_invoice_filter" model="ir.ui.view">
    <field name="name">sale.agreement.account.invoice.search</field>
    <field name="model">account.invoice</field>
    <field name="inherit_id" ref="account.view_account_invoice_filter"/>
    <field name="arch" type="xml">
        <group expand="0" position="inside">
            <filter string="Sale Agreements" name="sale_agreement_groupby"
                context="{'group_by': 'sale_agreement_id'}"/>
        </group>
    </field>
</record>


</odoo>