First of all, I cannot believe it is so hard or maybe impossible to get a simple BUY 1 FREE 1 functionality (BUY X FREE X).
Basically, what I'm trying to achieve is :-
1. I've 4 products (already add those products into a collection called 1-FOR-1 FREE)
2. Basically, if user buy 1 of this product, on the cart they will auto see 1 more same product with the price FREE.
3. If they add quantity 2, meaning they will auto see additional 2 more FREE. Meaning in total they will get 4 products.
4. If they buy all 4 products with quantity of 1 each, meaning they will auto get another 1 FREE for all those 4 products. Meaning in total they will get 8 products with a price of 4 items.
Obviously, the free function from Shopify doesn't support this type of simple discount. Any suggestion for plugin that can do this?