If we need to set a price for a group of the same item (belonging to the same line item selector), we will use the processing function "Target Price for a Bundle" in the QC.
For example, we want to create a campaign using this QC called "2 Burgers for $10". We would set our Target Price to $10, select the Line Item Selector for "Burger", and set its quantity to "2".
In order to set this up, please contact your Customer Success Manager