[Answered ]-Many to One Relation in Django With Existing Objects

Your relationship is going the wrong way. If a Product can have multiple Items, make a ForeignKey from Item to Product. With the ForeignKey on Product, you’re saying each product has exactly one Item, but each Item can belong to multiple Products.

The docs have more details and examples:
https://docs.djangoproject.com/en/1.7/topics/db/examples/many_to_one/