Question on Vendor Rebate Arrangement

Is there a way to create a single Vendor Rebate Arrangement to cover all the materials procured from a vendor ? I can use TCode MEB1 to create a rebate agreement to cover a single material. But if I have to take advantage of the volume discounts offered by the vendor, I need to create a single rebate agreement to cover all materials procured. How can this be achieved ?

Any help is most appreciated. Thanks.