Administrator / test_3

  <?php
  use yii\helpers\Html;
  ?>
  <fieldset>
  

      <div class="field_list">

          <?php    $t = 0;

          $label = 0; // add this var
  
          for($i=1; $i <= count($model); $i++):
              $row = $i;
  
              ?>

  
          <?= Html::beginTag('div',['class'=>'form-group','id'=>isset($model[$i]['parent_key']) ? $model[$i]['parent_key'] : 0 ])?>

              <div class="input-blocks">
                  <label for="cont-site-<?= $label ?>">Сайт</label>
                  <input id="cont-site-<?= ++$label  ?>" type="text" placeholder="" class="form-control custom-input-2" value="<?= isset($model[$t]['value']) ? $model[$t]['value'] : '' ?>" name="Fields[site][<?=$row?>][0][site]" />
              </div>

              <span data-id="<?= isset($model[$i]['parent_key']) ? $model[$i]['parent_key'] : 0 ?>" title="удалить" class="glyphicon glyphicon-trash delete-field-item"></span>
          <?= Html::endTag('div')?>
          <?php $i = ++ $t; ?>
      <?php endfor; ?>

      </div>

      <p class="btn btn-success add_field_<?= $this->context->id ?>">Добавить еще</p>

  
  </fieldset>
  <script>
      var start_i_<?=$this->context->id?> = <?=$i?>;

      var start_label_<?=$this->context->id?> = <?=$label?>; // add this var

      $( document ).ready(function(){
          $('.add_field_<?=$this->context->id?>').click(function(){

              var block     = $ (this)
                  .siblings('.field_list');

              var block_id =  $(this).parent('fieldset');
              var sub_block = '<div class="form-group" >'+

  
                  '<div class="input-blocks">'+
                  '<label for="cont-site-' + start_label_<?=$this->context->id?> +'">Сайт</label>'+
                  '<input id="cont-site-' + ++start_label_<?=$this->context->id?> +'" type="text" placeholder="" class="form-control custom-input-2" value="" name="Fields[site]['+ start_i_<?=$this->context->id?>++ +'][0][site]" />'+
                  '</div>'+

                  '<span title="удалить" class="glyphicon glyphicon-trash delete-field-item"></span>'+
                  '<div>';

  //            console.log(block);

              block.append(sub_block);
  
          });
      });
  </script>