Extend Trigger Area for idoc

Hello Experts,

we have extend an idoc in SAP CRM with z-fields. The transfer of the data to CPI is working fine but I am facing an issue concerning the trigger-relevant z-fields:

Example:

This is part of a contact person view in CRM. The red marked Divison fields are Z-Fields.

Usecase:

1) Flag Checkbox EFP - Click Save - No Idoc is generated. The CRM_BUPA_SAVE IDoc should be created.

Does anyone no how to extend the triggerrelevant fields for idocs?

BR Christof