Replicate Business Partner from SAP S4hana to SAP CPQ extension fields mapping

[BurakYilmaz]

Hello SAP Community,

I am working with the standard integration flow "Replicate Business Partner Relationships from SAP Master Data Integration", which is part of the SAP CPQ - Quote 2.0 Integration with SAP S/4HANA Sales Order package.

Our customer requires the handling of a custom extension field (ZZExtensionField) that exists on both systems (SAP S/4HANA and SAP CPQ).
In the iFlow, this field needs to be mapped to the Customfields structure in SAP CPQ. However, since the standard iFlow does not include a mapping for this field, I need to implement it outside the standard functionality.

Here are some additional details regarding my challenge:

The post-processing step in the iFlow only receives the message payload, and the mapping uses Exchange Properties.
If I want to use these Exchange Properties in the post-processing step, I would need to replicate all standard iFlow requests (e.g., OAuth and Business Partner Get requests) within the post-processing.
Questions:

Is there a way to pass Exchange Properties directly to the post-processing step without replicating all the standard requests?
What is the best approach to enhance the iFlow to handle such a scenario without disrupting the standard design?
Are there any recommended practices or examples for efficiently extending the iFlow for custom field handling?
Any guidance, documentation references, or examples would be greatly appreciated.

Thank you in advance!