title: Django Model Reference to Multiple Foreign Key with Child Property
body: <p>I have the following Models of customer details with each customers having different payment modes (eg. cash, online transfer, etc...) :</p>
  <pre><code>class Customer(models.Model):
      #some customer details
  
  class Payment(models.Model):
      customer = models.ForeignKey(Customer, on_delete=models.RESTRICT, related_name='payments')
      payment_mode = models.CharField(max_length=255, blank=True, null=True) 
  </code></pre>
  <p>And I would like to add a new Invoice Model to include the customer as well as the customer's payment modes.</p>
  <pre><code>class Invoice (models.Model):
      customer = models.ForeignKey(Customer, on_delete=models.RESTRICT, related_name='payments')
      payment_mode = models.ForeignKey(Customer.payments.payment_mode, on_delete=models.RESTRICT)
  
  </code></pre>
  <p>I am going to create an Invoice for a customer and will input the customer's available payment mode. But the the invoice's payment mode is giving me an AttributeError: 'ReverseManyToOneDescriptor' object has no attribute 'payment_mode'.</p>
  <p>May I know how do I set up the reference to the customer's child data?
  Thank you.</p>