Hi Cristina,

Thanks for contacting us here.

For your information, it's impossible to add a smart bundle to another composite product or smart grouped product. These special product types are equal and work individually.

In case you would like to extra products to a smart bundle or composite product, then use the WPC Frequently Bought Together or WPC Force Sells plugin.

You can use the WPC Frequently Bought Together plugin to add optional extra products to a smart bundle/ grouped product/ composite product. 

Or use the WPC Force Sells plugin to add required extra products to a smart bundle/ grouped product/ composite product. 

These extra items will be displayed under the main bundled products/ grouped products/ component products on that product page. 

NOTE: Both Bought Together and Force Sells items can be added to the same main product so that you can have both optional and required options in a single offer.

For more information, you can kindly refer to the online documentation of our plugins on this site: https://doc.wpclever.net/.

We also have a blog about how to combine plugins, you can obtain some more information here: https://wpclever.net/5-best-woocommerce-product-bundling-tools-for-skyrocketing-your-sales.

In case you need help wit setting up your deal, you can kindly describe it in detail so that I can help you with combining WPC plugins to achieve the goal. 

Best regards.