Free goods of different material

Hi Experts,

I have mapped free goods scenario in our system.Its working well for inclusive and exclusive free goods for same material. i.e. If I have a material M1 ordered for 100 units I will get 10 units of the same material M1 free(Exclusive) and two line items generated TAN and TANN.

Similarly for inclusive condition,We have a material A1. If one orders 100 units of A1 he has to pay for 90 units only(TAN) and the remaining 10 units (TANN) comes for free.

Now I want to set up the system in such a manner that If the customer orders a material R1 of 100 units he will get material R2 of 10 units for free.

How do we do this setting? In NA00 itself? If yes please tel me the steps involved.

Regards,

Randhir