Hi Paul. You have a lot going on with your question so I’m not sure how to answer with confidence, but I’ll give you some thoughts. It is standard behavior that once a task starts, the start date and % complete is locked. Actual work doesn’t move). When you update a task, make sure you set the Actual Start date first, then set % Complete or however you are updating actual work. My assumption is that you aren’t trying to move the part of tasks that are already started/completed. Changing predecessors after that will only change the remaining work. I also prefer using Fixed Work or Fixed Units as a default task type than Fixed Duration.