Discount on product with options

Hi,

I have a question about setting discounts on a product with options.

This is the product with 2 options (1.5 kg and 4.5 kg), both having their own SKU, price and weight.




For the first option (1.5 kg) the base price is used as set on the tab 'Data'.
For the second option (4.5 kg) a certain amount has been added to the price.

Now my customer want to give a discount on both products to certain customergroups.
But I can't find where to set that discount, because the tab 'Discount' doesn't offer me all settings, I guess.
I can set a discount, but I can't choose the specific option of that product.

I want to give € 5,- discount to the 1.5 kg product and € 10,- to the 4.5 kg product.




So I need some advise how to solve this iusse.

Best regards,
Burt