members = models.ManyToManyField(User, through='Role')

def __unicode__(self):
    return self.name


class Role(models.Model):
    person = models.ForeignKey(User)
group = models.ForeignKey(Event)
date_joined = models.DateField()
invite_reason = models.CharField(max_length=64)
Как создать таблицу тройного соединения с помощью Django