You can add UpSell, CrossSell and Downsell products to any product using the UpSell/CrossSell/DownSell section of the Pricing widget on the product overview page. You can also add these items to any product using Bulk Edit and Bulk Import. You can reorder the products in each section by dragging the grab bars on the left of each product and dropping it in the desired position. You can delete products from each section by clicking the trash can icon.
When a product has UpSell or DownSell or CrossSell defined in the pricing widget is added to a quote, the corresponding icon will display on the quote.
Clicking the UpSell or DownSell link will display a modal with the respective options as radio buttons. Selecting one of these options will replace the item it is associated with on the quote.
Clicking on the CrossSell link will display a modal with check boxes. You can select multiple items from the CrossSell link to add to the quote.