Production Order Custom Field. APO to ECC. How to populate?

Hi Experts,

We have a custom field on 'CustomerSpecificValues" tab in Production Order in ECC.

In ECC, this is populated during Order creation(CO01) via a User Exit (ZXCO1U11).

But, when Production Order creation is triggered in APO via CIF (Inbound Queue), above exit is not called and the field remains blank in ECC.

I'm new to SAP APO and wondering how to implement this.

Can somebody point me in the right direction.

Thanks,

Bhuvan