Select checkbox dropdown inside select checkbox dropdown?

I want to create a Select checkbox list under the Select Checkbox dropdown again. What do I have to do?

Sample i need

☑ C 1 : name

       ☐ C 1.1 : name

       ☑ C 1.2 : name

☐ C2 : name

☐ C3 : name

My code

form views

     <label>Standard List</label>
            <select type="button"id="framework" name="framework[]" multiple class="form-control" >
            <option class="dropdown-toggle" id="dropdownMenuButton" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false" value="Codeigniter">Codeigniter</option>
            <option value="CakePHP">CakePHP</option>
            <option value="Laravel">Laravel</option>
            <option value="YII">YII</option>
            <option value="Zend">Zend</option>
            <option value="Symfony">Symfony</option>
            <option value="Phalcon">Phalcon</option>
            <option value="Slim">Slim</option>
            </select>

Js :

      $(document).ready(function(){
     $('#framework').multiselect({
    nonSelectedText: 'Choose...',
     enableFiltering: true,
      enableCaseInsensitiveFiltering: true,
   buttonWidth:'400px'
   });
  });