Inventory Commitment

I am wondering if someone can help me. My goal is to allow backordering only at print pick slip. In other words, I dont want any order lines to go on backorder during order intake (P4210). I have availability check and backorders enabled on item master, item branch, customer master. In P4210, I set the activate availability checking to 2 (Activate, notify, but do not backorder or cancel). With this said, i expect no lines to go on back order during order intake in P4210. However, i ran multiple tests and these all go on backorder despite the processing option.