# Add sub-collections to filter option
✨The smart product filter & search app provides a feature to add sub-collections to the collection filter option. It will allow you to create a collection tree as in the below screenshot.
📝 Note: This feature only works with **Filter Options** whose **Data source** is **Collection!**
### ⚡️Step 1: Add the Collection filter option
1. Open the **Smart Product Filter & Search** app from your Shopify admin.
2. Go to the **Filters** section (in the left-hand menu).
3. Open the filter sidebar you want to edit (e.g., “Collection Page” sidebar).
4. Click **+ Add filter option**.
5. Choose **Collection** as the Source.
6. Turn ON the checkbox that says **Build a collection tree with multi-level sub-collections**.
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### ⚡Step 2: Set Up Parent-Child Collection Structure
* To define a **main collection (parent)** and **sub-collections (children)**, Drag and drop collection values to the expected position to build a collection tree.
* Remove any collections by clicking the **X** icon.
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### ⚡️Step 3: Save and Preview
Once you've added the Collection filter option, click **Save**.\
Go to your storefront and check the filter sidebar. You should now see collections displayed in a tree format (with sub-collections nested under parent ones).
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### 💬 Need Help?
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