Close standard change automatically after Post Implementation Review task is closed

[TEdwards]

I need to write a Wait for Condition script for our Standard Change Workflow so that I can set the value for the change to close automatically after the post implementation review task is closed. Our current workflow is attached. We use a subflow for the change tasks, so I assume I would need to write the script to wait for that subflow to complete, but I am not quite sure how to go about it. Can anyone assist?

[TEdwards]

This is what I was trying to do initially, but I was not sure how to write the script. I guess the script is what I was really after.