Question 1: Can I add a grouped product or a composite product to another bundle to use as a bundled product?
Answer: No. All products created by WPC Product Bundles, WPC Composite Products, or WPC Grouped Products plugin are of equivalent product types.
You can observe that fact when choosing a product type from the Product Data drop-down list. Therefore, smart bundles, composite products, and smart grouped products CANNOT be added inside one another. Even if you can search for and add them in the back-end, but in the front-end, they won’t be visible or functional as normal.
In order to add extra items to a Smart Bundle, Composite Product, or Smart Grouped, you can use WPC Frequently Bought Together or WPC Force Sells plugin. After installing these plugins, users can add extra products in the Bought Together tab or Force Sells tab.