partner-contact/partner_firstname/views/base_config_view.xml

<?xml version="1.0" encoding="utf-8"?>
<!-- © 2015 Antiun Ingenieria S.L. - Antonio Espinosa
     License AGPL-3.0 or later (http://www.gnu.org/licenses/agpl.html). -->
<odoo>

<record id="view_general_configuration" model="ir.ui.view">
    <field name="name">Add partner_names_order config parameter</field>
    <field name="model">base.config.settings</field>
    <field name="inherit_id" ref="base_setup.view_general_configuration"/>
    <field name="arch" type="xml">
        <xpath expr="//label[@name='email_label']/.." position='after'>
            <group>
                <label for="partner_names_order" />
                <div>
                    <div>
                        <field name="partner_names_order" class="oe_inline" />
                        <field name="partner_names_order_changed" invisible="1"/>
                        <button name="action_recalculate_partners_name"
                                string="Recalculate names"
                                icon="fa-play"
                                type="object"
                                help="Recalculate names for all partners. This process could take so much time if there are more than 10,000 active partners"
                                attrs="{'invisible': [('partner_names_order_changed', '=', True)]}"/>
                    </div>
                </div>
            </group>
        </xpath>
    </field>
</record>

</odoo>