SRC SC to ECC PO - Pass "Requirement Urgency" field

We are using ECC 6.0 and SRM 7.1 in Classic scenario.

We have a requirement to pass standard field on PR “Requirement Urgency”(PRIO_URG) to custom field on SRM Shopping Cart, when PR is created in ECC.

Also, if Shopping Cart is directly created in SRM, we need to pass this field to ECC PO.

I tried BAdI BBP_CREATE_BE_PO_NEW, but

• It is not passing the field value to ECC PO for some reason. (I tried passing TRACKING_NO field; could not debug as it may be triggered in background)
• It does not contain “Requirement Urgency”(PRIO_URG) field.