Simple product Stopping quantity Product grouped from work

I am running M2.2.0 and I have created a store that only sells 4 products (bottled beer), although my problem is this: the boss only wants to sell them in the case of 8 bottles. I have configured a simple product for each beer with a price per bottle and I edited the Advanced Inventory so that it has a Min Qty of 8 and an increase of 8 so that customers do not order values ​​of 6, 10, 3, etc. Am I wondering how I can now make a mixed case containing 2 bottles of each beer? A grouped product is rejected on the cart page because the number of bottles is 2 instead of 8.

Things to keep in mind: I'm new to this, so please be patient with me and accept the novice mistakes. The simple products are not visible, but I have configured grouped products for each beer with a default value of 8 bottles.