# How-to Guides

## Managing Usage Product References

Within Usage Product Inventories, there can be one or more usage product references (e.g., telephone numbers).

**Adding References:**

When creating a Usage Product Inventory, specify references as a list in the initial request.

**Adding Additional References:**

Use the `add` operation on `PATCH /usage-product-inventories` endpoint to add more references after creation.

**Updating Individual References:**

Use the `add` or `replace` operation on the `PATCH /usage-product-references` endpoint to update specific references.

Read more about [JSON Patch operations](http://jsonpatch.com/).