How to Update New Process Variables for Existing Active Process Instances?

Hi Appian Community,

I have a situation involving a process model and a process report.

I have a process report that retrieves process variables from active process instances and displays the data.

For example, suppose we have an existing process model with several process variables. In the future, we add new process variables and need to populate those variables for existing active process instances.

My understanding is that we can use “Upgrade Process” to upgrade the existing active instances to the latest process model version. However, the newly added process variables remain null because the nodes that populate those variables were not executed in the original process instance.

The challenge is that I cannot simply restart or manually trigger the new node because the process instance are more, and that node was not part of the execution path when the instance originally started we cannot use “Restart Node” smart service.

My requirement is:

1. Upgrade existing active process instances to the latest process model version.
2. Execute the newly added node(s) for those existing instances.
3. Populate the newly added process variables.
4. Make those values available in the process report for the older active instances.
5. Ideally, this should happen without manually restarting or creating new process instances.

Has anyone implemented a solution for this scenario in Appian?

Is there a recommended approach to execute a newly added node on already-running process instances after a process upgrade, so that the new process variables can be populated?