Multiple Items Within a Product

Hi support please help me out, I want to know that is it possible to include multiple items(with variations) within a product? My actual product is a mattress and I want to include a additional “mattress cover”(with price variations) with this product order, and it will be the choice of the customer to select this additional item or leave it ?
Also, is it possible to put the coupon code on this product page just below the variations dropdown?

http://ww.wp.xz.cn/extend/plugins/woocommerce/