add functionality to django model admin class. To use separate forms for adding and updating data

main.py

class ExtraAdminUtils(admin.ModelAdmin):
    add_fieldsets: dict = None
    add_form = None

    def get_fieldsets(self, request, obj=None):
        if not obj and self.add_fieldsets is not None:
            return self.add_fieldsets
        return super().get_fieldsets(request, obj)

    def get_form(self, request, obj=None, **kwargs):
        """
        Use special form during user creation
        """
        defaults = {}
        if obj is None and self.add_form is not None:
            defaults['form'] = self.add_form
        defaults.update(kwargs)
        return super().get_form(request, obj, **defaults)