I know the title doesn't make sense so I will try to explain.
I would like a customer to be able to add an additional product to there order via the product they are already looking at.
If the customer adds product 1 to there basket, before they have to go check out and instead of searching for the second item I would like it to be linked to the first listed product, like an additional item - not so much as a related product but as a product option. I know there is options you can add to the product but it seems to be more like colour or size.
so for example. I add a notebook to my cart but as I do that it gives me an option to add a red pen, it updates your basket and price and then you can just check out.
is this an option in the standard install of opencart.
sorry if it doesn't make sense and thanks for taking the time to read.