odoo-purchase-addons/purchase_discount_without_stock/views/res_partner_view.xml

<odoo>
    <record model="ir.ui.view" id="res_partner_form_view">
        <field name="model">res.partner</field>
        <field name="inherit_id" ref="base.view_partner_form" />
        <field name="arch" type="xml">
            <xpath expr="//group[@name='purchase']" position="inside">
                <field
                    name="default_supplierinfo_discount"
                    attrs="{'invisible': [('is_company', '=', False), ('parent_id', '!=', False)]}"
                />
                <div
                    name="supplierinfo_discount_disabled"
                    colspan="2"
                    attrs="{'invisible': ['|',('is_company', '=', True), ('parent_id', '=', False)]}"
                >
                    <p>Discount-related settings are managed on <button
                            name="open_commercial_entity"
                            type="object"
                            string="the parent company"
                            class="oe_link"
                        /></p>
                </div>
            </xpath>
        </field>
    </record>
</odoo>