Negative price for custom items

carts

#1

Hi there !
I would like to apply specific discount to specific products or pack of products.
To do that I wanted to use the custom item feature that would permit me to calculate discount based on some of the cart products.
But I just understood that it is not possible to use negative values as custom item price.
It is very blocking to me please can you help me find out a workaround ?

EDIT: Could you detail the way this sentence is supposed to be possible please ? “Dynamically create a special bundle price for a combination of products” - https://moltin.com/blog/2017/05/introducing-custom-line-items