Adding Fields to Registration Form [or Multiple Inheritance of forms]

from registration.forms import RegistrationForm
from django.forms import ModelForm
from models import Organization

class OrganizationForm(forms.ModelForm):
    class Meta:
        model = Organization

RegistrationForm.base_fields.update(OrganizationForm.base_fields)

class CustomRegistrationForm(RegistrationForm):
    def save(self, profile_callback=None):
        user = super(CustomRegistrationForm, self).save(profile_callback=None)
        org, c = Organization.objects.get_or_create(user=user, \
            logo=self.cleaned_data['logo'], \
            name=self.cleaned_data['name'])