Cart Rule: 2+1 (and multiple) issue

[Maxmito]

Cart Rule problem:
I have a website where I setup various cart rules: 2+1(free), 5+1(free), 8+1(free) etc... all of them compatible to make the discount "scalable".
The problem is that when there are 2 of them combined, the discount is applied always to the cheapest product, causing  issue with invoicing.

Example:
A: 5 euro B: 5 euro C: 5 euro D: 4 euro E: 3 euro F: 2 euro.
With this cart both 2+1 and 5+1 are applied, but it count the discount always on the cheapest product (Fx2, 4 euro) and not on the 2 cheapest E+F= 5 euro.
Do you know any way to get this done?