Will an EDI 830 RLM Schedule recognize a manually created RLM schedule in OM Lines?

I recall reading this somewhere years ago but cannot find this confirmation.  Scenario:  I enter a Manual RLM Schedule because Nissan wants to ADD a RAN number to ship today for an item.  I enter all pertinent data in RLM Workbench including DFF RAN Number.  IT creates a new SO Line correctly.  The next day Nissan sends a new 830 schedules with ths ADD RAN item.  Should the DSP recognize this previously entered Manual item/RAN in OM Sales ORder?  My testing says NO and creates a duplicate item/RAN SO Item.

Can someone please confirm my suspicion as client is under impression it SHOULD recognize and match to SO Line.  There must be some disconnect in he process that will not allow matching and thus creates a duplicate line and RAN.