title: Multiselect dropdown/list in django admin panel only
body: <p><a href="https://stackoverflow.com/questions/3582544/django-model-choice-option-as-a-multi-select-box">django model choice option as a multi select box</a></p>
  
  <p><a href="https://stackoverflow.com/questions/2726476/django-multiple-choice-field-checkbox-select-multiple">Django Multiple Choice Field / Checkbox Select Multiple</a></p>
  
  <p><a href="https://stackoverflow.com/questions/15393134/django-how-can-i-create-a-multiple-select-form">Django: How can i create a multiple select form?</a></p>
  
  <p>I'm trying to add a multiselect field in existing django model.
  I went through these three SOF threads and some other blogs but I didn't find required solution. everyone is using modelForms.</p>
  
  <p>I want this in purely in default django admin panel (same as choice field).
  this field is not going to be used in front-end/any kind of form. purely for admin purpose.</p>
  
  <p>How can I achieve this.</p>
  
  <p>I can create another model for this and then ManytoMany relation but I wonder if there exist
  some thing like</p>
  
  <p><code>field = models.MultipleChoiceField(choices=[a list of choices])</code></p>