Hello,
I have up against a similar problem and wondering if anyone has a solution. I ideally want to create product pages that have the primary add to cart button for the sku on the page, but then also show related products that I can manually select with corresponding add to cart buttons. Examples from non shopify stores include:
https://www.thegardengates.com/folding-metal-chairs-p7645.aspx
http://www.potterybarn.com/products/antique-silver-sentiment-pitcher/
It is essentially showing "you may also like" items, but helping to improve conversion by allowing the customer to add to cart right there on the page. Ideally, the related product titles would be hyperlinks to their corresponding pages, but that is not a must.
Thanks in advance,