'Custom save method to add data to the through model.'

def save(self, *args, **kwargs):

    for profile in self.cleaned_data['invites']:
        if (not Invite.objects.filter(group=self.instance, redeemer=profile).exists()):
            (invite, created) = Invite.objects.get_or_create(group=self.instance, redeemer=profile, inviter=self.request.user.userprofile)
            notify_redeemer_invitation.delay(invite.pk, self.instance.invite_email_text)
