Hi Peter,

I do not know exactly what is promotion type that you are using for this setup? As I know then you completely choose sku 1 and 2 for eligible items. So it is unnecessary to exclude sku 3 and 4.

You also can use excludedCatalogItems if you have promotion settings like:

• Eligible items: all items belong category "A"

=> You may need to use excludedCatalogItems if you want to exclude some products that belong to category "A"

It depends on the type of your promotion, but many promotions inherited from EntryPromotion has a PurchaseQuantity Condition, where you can set the list of items that are allowed for the promotions, basically

promotion.Condition.Items = new List<ContentReference>() { itemA, itemB }; 

Peter - "I see I can edit a promotion and add ExcludedCatalogItems to the promotion Data so that some items aren't on sale.  But my question is how do I create a promotion and add items to the sale?"

For this particular requirement & if you do not want to create a custom promotion then you can do the following solution.

1 - Create a Visitor Group of Criteria "Item in Basket or wish list" - Add SKU 1 and 2 in it.

2 - Now create a promotion where one of your qualifying criteria should be your Visitor Group.