https://experienceleague.adobe.com/docs/experience-manager-learn/forms/interactive-communications/merge-data-with-ic-template.html?lang=ensee if this helpsif not we can get on a call

Which servlet are you calling from postman?

Yes read this article https://experienceleague.adobe.com/docs/experience-manager-learn/forms/ic-print-channel-tutorial/opening-agent-ui-on-form-submission.html?lang=en

Interactive communication (IC) has to be based on FDM. The FDM allows you the map data elements from your backend source into your IC.prefill service is typically used with agent Ui who want to open a IC by fetching information from the backend source using a specific key such as an account number 

Since you are creating a endpoint that will fetch and returns the necessary data that will be consumed by your interactive communication, you can make changes as you needthe prefill service is used to prepopulate form or interactive communication when it is being rendered  

Only one form data model per interactive communication you will have to create a servlet which will return the appropriate data from various sources and then create form data model to model the data returned by this servlet 

Forms add on for Mac does not support pdf generation we recommend  you use either windows or Linux operating systems 

Can you please send us the form?we will take a look and get back to you 

https://experienceleague.adobe.com/docs/experience-manager-learn/forms/zipping-form-attachments/populating-list-of-documents.html?lang=en

I will send you something soon