Checkbox to add additional item to cart at reduced rate?

Hello, I would like to be able to offer certain items at a discounted rate when a customer buys a specific item but I’m having trouble getting exactly what I want.

I have a craft product and in a separate listing have extra craft supplies. I want to be able to offer the extra craft items at a discount when purchasing the main product. For the most part, I’ve achieved the discount by purchasing Woo Discount Rules PRO but it only mentions the discount in the listing for the extra supplies. I want it to mention the discount in the main product listing too or else no one will know it is there. How can I achieve this?

Also, is there a way to just have a tick box on the main product listing which mentions the extra supplies and you just need to click it and it will add it to the basket, so customers don’t have to actually go into the other listing?

On a similar note, I want to offer virtual downloads of my books at a reduced rate when buying the physical book. As before, a check box that says something like, “check this box to add X to cart at 50% off” for example.

Like I say, I’ve bought Woo Discount Rules PRO but can’t see a way to do that?

Thank you.