Ohh k, I though it was a bug but it doesnt seen to be very hard to do since the the prices are taken in to account they just need to be displayed, I think this changes have to be done in the invoice creation also in the order view.
this feature has to be useful for everyone, Ill try to do that but my php skills are not that good.
Also is there another way to do this?
May be with parent and child products or somethign?
Thx for your time.