additional alternatives bit blue button cart click cost customer default don down drop example multiple order product products redirect select selects shorts show simplest t-shirt up-sell variant

I've been looking for a bit now and cant find the answer, so please redirect if it is out there.

I would like to add multiple products to my cart via drop down alternatives with one add to cart button:

Let me give you an example:
Customer selects a product and I want to them to up-sell an additional product in the simplest possible way...

I would like me customer to choose from a drop down their first product the its variant i.e. t-shirt (blue)
I would also like them to choose their second product i.e. shorts (XL) from a second drop down, I would then like them to add all that to the cart in one click.

But what if they don't want the shorts?! well the default on the drop down would be "Select if you want some shorts" with the variant for "Select if you want some shorts" being cost 0.00.

i.e. select... will show up on the order, but at 0.00 cost.

is this possible?