Using Timesheets in PWA but how to prevent changes to forecast

Alison Howes We do something very similar to this. It's not the most elegant solution, but it's robust and relatively simple. Each project is split into two WBSs, one for a minimal number of time reporting tasks and the other for forecasting/planning tasks. The time reporting section is straight forward, but we do keep the number of time reporting task to a "meaningful" level (very subjective). However, the forecasting tasks have a different process to following:

• Resources are assigned to tasks that are setup on a monthly basis.  This allows you to assign resource to task for the months they work, and you can adjust the allocation % from month to month as needed
• No time reporting on these tasks....ever
• Never status or mark these tasks as finished.  We also setup them up as manually scheduled tasks to help prevent them from being accidently updated.
• Baselines - We don't use them, but may in the future.  We've used them in the past, but baselining processes tend to get complicated and time consuming, especially when your org has many projects (we have several thousand projects active). 
• Users can view the rolled up forecast numbers within the plan, but this data is pulled with Power BI and we a set of reports that compare the Actuals vs Forecast (remaining) by work (hours or FTEs), costs and the values can also be displayed as %.

The process also allows for the forecasting to be done in a separate project, for example at a program level.  This is done when the user has a lot of smaller projects and it's just not practical to setup forecasting tasks in dozens of projects.  When done this way all analysis is down in Power BI.

As mentioned earlier, this is a pretty simple solution and may seem arduous, but in the all the years I've been doing this, it's the only method that has been widely adopted, which I believe is contributed to it's simplicity.  However, I'm always looking for better solutions and look forward to seeing how others tackle this.