Django multi tennant architecture - Should all models have a reference to the tennant_id

Let's say that accounts in my SAAS are of the type Account(models.Model). Would the following be a good idea?

class MyModel(models.Model):
    account = models.ForeignKey(Account)
    spam = models.CharField(max_length=255)

class MyOtherModel(models.Model):
    # The next attribute `account` is the line in question.
    # Should it be included even though mymodel.account can get the same value?
    # The architecture could change later, and I might regret not including it,
    # but I can't think of many reasons why, other than filtering a list out of
    # this model like MyOtherModel.objects.filter(account=some_account).all()
    # Are there other considerations?
    account = models.ForeignKey(Acc开发者_如何学运维ount)
    mymodel = models.ForeignKey(MyModel)
    eggs = models.CharField(max_length=255)

If you don't have a use for it now I'd leave it out. Code what you need now, refactor if necessary later. There are a few tools out there that make schema changes more painless. South is a great example - works well in many situations, continues to mature, and has great community support behind it. django-evolution is another option It has been around for a while, development on it has dropped off, but it offers an approach that some people still favor.