Hi,
Two products in cart, one common product and one without shipping fees. Should the shipping fees be applied on one of the two products, or shall the whole cart be without shipping fees ?
If in the shipping method, you set a value, for example $3, for the option "Price" and enable "Use price per product" and set "-3$" in the product edition page of the desired product, so the whole cart we be shipping fees less.
If you set $3 for the option "Price per product" after enabling "Use price per product" and set "$0" in the product edition page, so the shipping fees will be equal to "$3", or "$6" if you have two times the product without shipping fees.
Do you see what we are asking ?