Extended Family allows you to easily configure cross sells from an admin panel without the need for additional discounting.
Cross sell items are displayed on the product info page of products you have set up with Extended Family items.
When eligible, items are displayed with a checkbox - checking the checkbox allows them to be added to the cart right along with the main item when the Add to Cart button is pressed. As you might expect, the checkbox follows the same rules that adding a product from the listing page does: in order to show the checkbox,
- The item must not not disabled (out of stock or otherwise).
- The item must not have non-defaultable attributes. (See my Default Attribute contribution)