Create a discount rule on a product that does not conflict with the cart with other products

[ballashop]

HI,

I would like the discount to be applied only to the certain product, but the rule also applies to the other products inside the cart!
How to solve?
Does Prestashop by default have this possibility or should it be necessary take a look external modules?

Ex:

I create a cart rule that is applied when there is a certain product into the cart:

Example cart:
product#3 (5% discount)
+ product#1
+ product#2

how do I tell prestashop to apply 5% only to a product#3?

I cannot apply the rule directly to the product because the rule must apply only to a certain customer. The customer is not yet registered and the discount is made to motivate him to buy obviously!

I use PS 1.6.1.24

Thanks a lot for any reply.