Add a "+" button that opens a popup inside my django model form

Question

I want to add a "+" button that opens a popup inside my django model form.. Any idea about that?

My code in models.py

class library(models.Model):
    book_name = models.CharField(max_length=50, null=True, blank=True)
    author = models.ForeignKey(User, on_delete=models.CASCADE, limit_choices_to={'is_superuser': True}, null=True,
                               blank=True)
    description = models.TextField(null=True, blank=True)
    duration = models.DurationField(null=True, blank=True)
    date = models.DateField()
    book_image = models.ImageField(upload_to='lib/book_img', null=True, blank=True)

parallel to author field i want to add a "+" button(To add new author) that opens a popup modal form.

my forms.py is

class library_details(forms.ModelForm):
    class Meta:
        model = library
        fields = "__all__"