> For the complete documentation index, see [llms.txt](https://knowledge.out-smart.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://knowledge.out-smart.com/backoffice/backoffice/items-and-materials/use-sub-items-and-parent-items.md).

# Use sub-items and parent items

Link related items so you can add supporting materials together with the main item.

Use sub-items when one item usually goes together with another.

This helps you register complete material sets faster.

{% stepper %}
{% step %}

### Open the parent item

Go to **Items**.

Open the item that should act as the parent item.
{% endstep %}

{% step %}

### Open the sub-item section

Go to the **Sub-item** section of the item.
{% endstep %}

{% step %}

### Add a linked item

Click **Add**.

Select the item that should be added as the sub-item.
{% endstep %}

{% step %}

### Choose the quantity type

Select either:

* **Fixed quantity**
* **Variable based on number of parent**
  {% endstep %}

{% step %}

### Set visibility and billing

Choose whether the sub-item should be **Visible** and **Billable**.

Then save the setup.
{% endstep %}
{% endstepper %}

### When sub-items are useful

Use them for combinations such as:

* a fixture with a matching accessory
* a device with installation materials
* a main part with consumables

### Frequently asked questions

<details>

<summary>What is the difference between fixed and variable quantity?</summary>

**Fixed quantity** always adds the same number.

**Variable** scales with the quantity of the parent item.

</details>

<details>

<summary>Do sub-items work on work orders only?</summary>

No.

You can also use them in quotations and invoices.

</details>

<details>

<summary>Can sub-items be added automatically?</summary>

Yes.

That depends on your work order settings.

</details>

### Related topics

* [**Create an item**](/backoffice/backoffice/items-and-materials/create-an-item.md)
* [**Work Orders**](/backoffice/backoffice/work-orders.md)
* [**Items and Materials**](/backoffice/backoffice/items-and-materials.md)


---

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