Trying to consolidate multiple shipment numbers in single ST order by updating promised deliverydate

Hi Community, We are trying to consolidate multiple shipment numbers in single ST order by updating the promised delivery date.

when we update the promised delivery date thru P4210 it does not update the single shipment number for all the lines, however the date is updated for all the lines.

It creates new shipment numbers for the lines (More than one in our case).

Below are the steps for replication -

Put ST/OT on a load

Approve the load

Add a new line to ST

Unapproved the load

Change the dates thru P4210 – it does not merge the shipments now