How to use SLA rules to generate Project Number COA segment in billing offset

Summary:

Project number is CoA segment, and is needed for project related transactions

Content (please ensure you mask any confidential information):

Client uses PPM Module for Costing and Billing, and also has the Project number as part of the Chart of Accounts. For all project transactions the specific project number to be included in the accounting string. We have achieved this in Costing, Billing & Revenue using SLA Configuration.

When comes to Billing offsets in Contract module for UBR & UER accountings, we are unable to call any rules created for Project segment.

Anyone had this requirement and discovered solutions using SLA rules to populate the project number in Billing offset?