Default store as empty value in customer creation page

Question

I would like to set default store value to empty value or 0 in stores dropdown list near field "Send Welcome Email From", in customer creation page.

I like also to receive an error when user keeps the empty value and when he don't choose a store value.

In cutomer_form.xml in module-customer, i found

<field name="sendemail_store_id" formElement="select">
        <argument name="data" xsi:type="array">
            <item name="config" xsi:type="array">
                <item name="source" xsi:type="string">customer</item>
            </item>
        </argument>
        <settings>
            <dataType>number</dataType>
            <label translate="true">Send Welcome Email From</label>
            <imports>
                <link name="value">${ $.provider }:data.customer.store_id</link>
            </imports>
        </settings>
        <formElements>
            <select>
                <settings>
                    <options class="Magento\Store\Model\System\Store"/>
                </settings>
            </select>
        </formElements>
    </field>

And in /vendor/magento/module-customer/Model/Customer/Attribute/Source/Store.php i found this function getAllOptions, is there the correct function to change it?

 public function getAllOptions($withEmpty = true, $defaultValues = false)
 {
    if (!$this->_options) {
        $collection = $this->_createStoresCollection();
        if ('store_id' == $this->getAttribute()->getAttributeCode()) {
            $collection->setWithoutDefaultFilter();
        }
        $this->_options = $this->_store->getStoreValuesForForm();
        if ('created_in' == $this->getAttribute()->getAttributeCode()) {
            array_unshift($this->_options, ['value' => '0', 'label' => __('Admin')]);
        }
    }
    return $this->_options;
}

EDIT:

Following this

<options class="Magento\Store\Model\System\Store"/>

I searched in class /vendor/magento/module-store/Model/System/Store.php, and found this function

public function getStoreValuesForForm($empty = false, $all = false)
{

    $options = [];
    if ($empty) {
        $options[] = ['label' => '', 'value' => ''];
    }
    ***$options[] = ['label' => '', 'value' => ''];*** // I added this, but how to set it as default?

    if ($all && $this->_isAdminScopeAllowed) {
        $options[] = ['label' => __('All Store Views'), 'value' => 0];
    }

    $nonEscapableNbspChar = html_entity_decode(' ', ENT_NOQUOTES, 'UTF-8');

    foreach ($this->_websiteCollection as $website) {
        $websiteShow = false;
        foreach ($this->_groupCollection as $group) {
            if ($website->getId() != $group->getWebsiteId()) {
                continue;
            }
            $groupShow = false;
            foreach ($this->_storeCollection as $store) {
                if ($group->getId() != $store->getGroupId()) {
                    continue;
                }
                if (!$websiteShow) {
                    $options[] = ['label' => $website->getName(), 'value' => []];
                    $websiteShow = true;
                }
                if (!$groupShow) {
                    $groupShow = true;
                    $values = [];
                }
                $values[] = [
                    'label' => str_repeat($nonEscapableNbspChar, 4) . $store->getName(),
                    'value' => $store->getId(),
                ];
            }
            if ($groupShow) {
                $options[] = [
                    'label' => str_repeat($nonEscapableNbspChar, 4) . $group->getName(),
                    'value' => $values,
                ];
            }
        }
    }

    return $options;
}

I added this

$options[] = ['label' => '', 'value' => ''];

The empty value is added but how to set it as default?

Please help.