Can’t add item into checkout_index_index.xml in Magento 2

I am using a theme purchased for my magento site and therefore have the onepage checkout. I would like to add the general conditions of sale on the last part but I cannot modify the template xml file. When I add the code to display the checkbox, the purchase tunnel crashes.

checkout_index_index.xml :

Before :

       </item>
                                                        <item name="shipping" xsi:type="array">
                                                            <item name="component" xsi:type="string">Magento_Checkout/js/view/summary/shipping</item>
                                                            <item name="config" xsi:type="array">
                                                                <item name="title" xsi:type="string" translate="true">Shipping</item>
                                                                <item name="notCalculatedMessage" xsi:type="string" translate="true">Not yet calculated</item>
                                                            </item>
                                                        </item>
                                                        <item name="grand-total" xsi:type="array">
                                                            <item name="component" xsi:type="string">Magento_Checkout/js/view/summary/grand-total</item>
                                                            <item name="config" xsi:type="array">
                                                                <item name="title" xsi:type="string" translate="true">Order Total</item>
                                                            </item>
                                                        </item>
                                                    </item>
                                                </item>
                                                <item name="itemsBefore" xsi:type="array">
                                                    <item name="component" xsi:type="string">uiComponent</item>
                                                    <item name="children" xsi:type="array">
                                                        <!-- merge your components here -->
                                                    </item>
                                                </item>

After :

                                                        </item>
                                                </item>
                                                <item name="itemsBefore" xsi:type="array">
                                                    <item name="component" xsi:type="string">uiComponent</item>
                                                    <item name="children" xsi:type="array">
                                                        <!-- merge your components here -->
                                                        <item name="after-place-agreements" xsi:type="array">
                                                            <item name="component" xsi:type="string">uiComponent</item>
                                                            <item name="displayArea" xsi:type="string">after-place-agreements</item>
                                                            <item name="dataScope" xsi:type="string">before-place-order</item>
                                                            <item name="provider" xsi:type="string">checkoutProvider</item>
                                                            <item name="config" xsi:type="array">
                                                                <item name="template" xsi:type="string">Magento_Checkout/payment/before-place-order</item>
                                                            </item>
                                                            <item name="children" xsi:type="array">
                                                                <item name="agreementss" xsi:type="array">
                                                                    <item name="component" xsi:type="string">Magento_CheckoutAgreements/js/view/checkout-agreements</item>
                                                                    <item name="sortOrder" xsi:type="string">100</item>
                                                                    <item name="displayArea" xsi:type="string">after-place-agreements</item>
                                                                    <item name="dataScope" xsi:type="string">checkoutAgreements</item>
                                                                    <item name="provider" xsi:type="string">checkoutProvider</item>
                                                                </item>
                                                            </item>
                                                        </item>
                                                    </item>
                                                </item>
                                                <item name="

I can’t understand why I can’t add items to this file without crashing my purchase tunnel

Head of this file :

<page xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" layout="checkout" xsi:noNamespaceSchemaLocation="urn:magento:framework:View/Layout/etc/page_configuration.xsd">
<body>
    <referenceContainer name="content">
        <block class="MagentoCheckoutBlockOnepage" name="checkout.root" template="Magento_Checkout::onepage.phtml" cacheable="false">
            <arguments>
                <argument name="jsLayout" xsi:type="array">

thank you