[Answered ]-Django admin manytomany field

I believe that you have misunderstood how the widget works.
Here is an example of the use of Django’s default widget for a ManyToManyField

Example: a teacher model is related to a language model:

teaching_languages = models.ManyToManyField('Language')

In the following case, English and Spanish are selected as values related to the teacher model, whilst French and German are not selected.
The green + sign allows you to add another language to the teaching languages list.