Reporting project progress using PWA

Question

My company uses the timesheeting system within PWA to record manhours spent and this is converted into progress by PWA. I set up an example project to demonstrate the issue I have.

The project has 2 tasks, each with 50 hours allocated to them.

If an engineer completes task 1 in 25 hours, he will enter 25 hours in the timesheet. PWA will record 25 hours of work done and the %Work complete will be 25% overall because 25 hours out of 100 have been worked. However, I want to report to our client that the project is 50% complete against the original plan because 50% of the planned workload as been completed.

How can I get PWA to report this? If I set the remaining hours to zero for task 1, it lowers the total project hours to 25 hours for task 1 and 50 hours for task 2 (75 hours) and then reports % work complete as 25/75 = 33% complete. I can't enter 50 hours in to the timesheet because this affects what we bill a client.