You can set a priority for each recommendation rule in the up and cross-sell recommendations. This priority determines the order of the recommendations for one product, with or without using a group key.

Let's say that you made four rules for the same product group. Products from all of these rules will be displayed under a certain product. Without using priority, these products are sorted using the recommendationID. Using the priority, you can set the order in which they should be shown yourself. If you would, for example, like to show sweaters first, then blazers, then blouses and finaally shirts & tops, then you can fill in priority 1 for sweaters, priority 2 for blazers and so forth.

This enables you to set a fallback as well. You may want to show four related products, but there are only three products that match the rule. This would mean that an empty spot will appear. You can prevent this from happening by creating a fallback recommendations rule and then giving the first rule priority 1 and the fallback rule priority 2.

You can set the priority here: