Tengo el siguiente código que ya trabajan bien en functions.php - quiero habilitar el día de las madres, aunque (12 de mayo de 2019) que cae en domingo. Cómo hago para agregar esto a la devolución de la cadena?

    function custom_adjust_datepicker_range () {
        if ( is_checkout() ) {

    ?>

    <script type="text/javascript">
    var disabledDays = [
     "1-1-2019","1-1-2020","2-1-2019","28-1-2019","27-1-2020","4-3-2019","2-3-2020","19-4-2019","10-4-2020","22-4-2019","13-4-2020","25-4-2019","25-4-2020","27-4-2020","3-6-2019","1-6-2019","30-9-2019","28-9-2020","25-12-2018","25-12-2019","25-12-2020","26-12-2018","26-12-2019","26-12-2020","27-12-2018"
    ];
    jQuery( "#delivery_date" ).datepicker({
        minDate: 2,
  beforeShowDay: function(date) {
    var day = date.getDay();
    var string = jQuery.datepicker.formatDate('d-m-yy', date);
    var isDisabled = (jQuery.inArray(string, disabledDays) != -1);
    return [(day != 1 && day != 0 && !isDisabled), ''];
}
});
    </script>
    <?php
        }
    } // End custom_adjust_datepicker_range()
    add_action( 'wp_footer', 'custom_adjust_datepicker_range', 50 );