material determination for 2 or more items.

Hi Gurus,

I'm trying to swap the meterial in material determination with option of 2 items...is it possible and if yes then how?

Normally, the single swapping is taking place in the sales order...but suppose if i want an option so that when i put the original material then the screen should give me 2 items or more to choose from for the swapping..how to configure this in the system.