如何覆盖用户值并保存到django中的另一个表中

Question

     I have a one model Product which have field location  and 1 another model name is Inventory movement in which product is foreign key. 
inventory movement model
            product_id=models.ForeignKey(Product)
            from_location = models.CharField("from location",max_length=30) 
            to_location=models.CharField("Locatiion",max_length=30)       
            user=models.CharField("Supervised By",max_length=50)
            remarks=models.CharField("Remarks",max_length=50) 
Product model. 
     product_id = models.CharField(max_length=100, primary_key=True)
        product_name=models.CharField("Product Name",max_length=50)
        location=models.CharField("Location",max_length=30)

首先，数据存在于产品模型中，现在我希望如果用户想要更改产品位置，则按库存移动形式进行维护。         现在，当用户在库存中输入to_location字段时，也会覆盖product.location字段，我该怎么做？