Как искать клиента (поле клиента aadhar) в таблице customer_billings как внешний ключ, и мы хотим сохранить другие поля в данных

Question

У меня есть 2 таблицы: customer и customer_billing

Как я могу отфильтровать строку customer_aadharnumber и связать две таблицы (из customer), чтобы сохранить обновленные customer_billing информация в базе?

Вот код модели:

class customer(models.Model):
    customer_Firstname      =  models.CharField(max_length = 20, null=True )
    customer_Fathername     =  models.CharField(max_length = 20, null=True)
    customer_Aadharnumber   =  models.CharField(max_length = 12, unique=True)
    customer_contact_no     =  models.CharField(max_length = 20, null=True)
    customer_address        =  models.CharField(max_length = 50, null=True)
    customer_advance        =  models.CharField(max_length = 50, blank=True)
    customer_created        =  models.DateTimeField(null=True,auto_now_add=True)

class Customer_Billing(models.Model):
    vehicle_number  =  models.CharField(max_length = 12, null=True)
    customer        = models.ForeignKey(customer,on_delete = models.SET_NULL, null=True)
    vehicle         = models.ForeignKey(vehicle,on_delete = models.SET_NULL, null=True)
    product_current_price       = models.ForeignKey(product_current_price,on_delete = models.SET_NULL, null=True)
    load            = models.CharField(max_length = 20, null=True)
    empty           = models.CharField(max_length = 20, null=True)
    Acurate_Mango_Weight    = models.CharField(max_length = 20, null=True)
    mango_suite     = models.CharField(max_length = 20, null=True)
    Final_price     = models.DecimalField(max_digits=1000, decimal_places=2)