How can I have both internal (sold by me) and Amazon products on my shop?

 Here's how the checkout will work:

If you have the on-site cart feature enabled and you have both products sold by you and products sold by Amazon in the cart (you will have to set the checkout to open in a new <> page in Amazon Config; you should warn your customers about pop-up blocking settings):

- a new page that redirects you to the Amazon's cart will open in a new tab, where you will be able to complete the order for the Amazon's products. Products sold by Amazon will be taken from your on-site cart.

- the products sold by you will remain on the cart (in the other tab) and the customer will be able to complete the checkout for your products, too.

 

 If you have the on-site cart feature disabled, then the customer will be redirected to each product's page on Amazon and the on-site cart will function just for products sold by you.