Customer Free Goods

We are doing some promotion for some items to have the free goods.

We need to maintain the fields of Item, Free Goods Item, Min. Qty, Buy Qty & Free Qty. When the customer buy item A, the item B is free of charge. It's apply to all customers.

But now, the management want to skip some customers that they don't need to give the free goods.

Where can we maintain the setting of the Free Goods in Customer level?