Django ManyToMany Through Relationship
<p>I have a following criteria </p>

<p>where I have User Model, which itself extended was from Django user model.</p>

<pre><code>Class User
   name = models.CharField()
   ...
</code></pre>

<p>A user can become a seller when he is approved by the admin. Seller model goes like this.</p>

<pre><code>Class Seller
    location = models.CharField()
    INDIVIDUAL = '1'
    COMPANY = '2'
    ACCOUNT_CHOICES = (
        (INDIVIDUAL, 'individual'), 
        (COMPANY, 'company'),
    )

    account_type_name = models.CharField(max_length=2,choices=ACCOUNT_CHOICES, default=INDIVIDUAL)
</code></pre>

<p>And Seller can belong to any of the second or third level categories</p>

<pre><code>Class Level1Category
    name = models.CharField()

Class Level2Category
    name = models.CharField()
    level1 = models.ForeignKey(Level1Category)

Class Level3Category
    name = models.CharField()
    level2 = models.ForeignKey(Level2Category)
</code></pre>

<p>When a user apply for seller account he has to select any one of the level 2 or level 3 category. Which would be the efficient model architecture for this. How can I link the category model with the seller and also link these two models with the user.</p>

<p><strong>EDIT</strong></p>

<p>My User Model is already a extended version of Django User Model. I'm doing that because I have two different type of profiles, one is seller and the other is buyer.</p>