[support] Ubertcart discounts problem

Hello, I need to apply a discount this way:

If three of a selection of products are added to basket pay only two.

I tried uc_coupons and uc_discount but can't find the way to do this.

The more similar ways I founded are: - apply a coupon with a 33.33% (not exactly what I need) If a selection of products sum a defined total. - apply a discount with multiple products selected and apply a 33.33% to each one (but I can't limit to 3, and the condition doesn't work es expected)

Another idea is to create a new product where I can select three of the original products.

Any idea of how to do that?

Thank's!

Pol