social/mail_parent_recipient/views/res_config_views.xml

<?xml version="1.0" encoding="utf-8" ?>
<odoo>
  <record id="view_configuration_mail_parent_recipient" model="ir.ui.view">
    <field name="name">mail.parent.recipient.config.settings</field>
    <field name="model">res.config.settings</field>
    <field name="inherit_id" ref="mail.res_config_settings_view_form" />
    <field name="arch" type="xml">
      <xpath expr="//div[@id='emails']" position='inside'>

        <div class="col-12 col-lg-6 o_setting_box" id="mail_parent_recipient_setting">
          <div class="o_setting_left_pane">
            <field name="use_parent_mail_address" />
          </div>
          <div class="o_setting_right_pane">
            <label for="use_parent_mail_address" />
            <div class="text-muted" id="mail_parent_recipient">
              Use partner's parent email if recipient partner has not email set.
            </div>
          </div>
        </div>

      </xpath>
    </field>
  </record>
</odoo>