Tricky issue passing data from form to form in django - django

Question

I am a django newbie and have one more big struggle for longer time... :/
User can choose a 'main language' which is set as ForeignKey. User can choose 'further languages' as ManyToMany (Checkbox). Assuming, user selects english as 'main' language, so english has to be filterd out from the 'further languages'... have been searching so much and have no idea how to do it. Is this even possible without JavaScript?
Of course, I could set the 'queryset' in the second form but it would filter the objects after the submit... The similar problem is, when a selected country has to be connected to the proper zipcodes...
I am very thankful for any hints.
Best regards.
class Country(models.Model):
enter code here
country = models.CharField(max_length=40)
active = models.BooleanField(default=True)
class Meta:
verbose_name_plural = 'Länder'
def __str__(self):
return self.country
class ZipCode(models.Model):
zipcode = models.CharField(max_length=5)
city = models.CharField(max_length=255)
active = models.BooleanField(default=False)
class Meta:
verbose_name_plural = 'Postleitzahlen'
def __str__(self):
return '{0} {1}'.format(self.zipcode, self.city)
class MainLanguage(models.Model):
language = models.CharField(verbose_name='Hauptsprache', max_length=40)
active = models.BooleanField(default=True)
class Meta:
verbose_name_plural = 'Hauptsprachen'
ordering = ['language']
def __str__(self):
return self.language
class SecondLanguage(models.Model):
language = models.CharField(verbose_name='weitere Sprachen', max_length=40)
active = models.BooleanField(default=False)
class Meta:
verbose_name_plural = 'weitere Sprachen'
ordering = ['language']
def __str__(self):
return self.language
class CustomUserprofile(models.Model):
user = models.OneToOneField(User)
name = models.CharField(verbose_name='Vorname', max_length=40,
null=True, blank=True)
country = models.ForeignKey(Country, verbose_name='Land',
null=True, blank=True)
zipcode = models.ForeignKey(ZipCode, blank=True, null=True)
main_language = models.ForeignKey(
MainLanguage, verbose_name='Hauptsprache',
null=True, blank=True)
second_language = models.ManyToManyField(
SecondLanguage, verbose_name='weitere Sprachen',
null=True, blank=True)
class UserProfileForm(forms.ModelForm):
second_language = forms.ModelMultipleChoiceField(
queryset=SecondLanguage.objects.all(),
required=False,
widget=forms.CheckboxSelectMultiple)
class Meta:
model = CustomUserprofile
exclude = ('user',)