I'm not sure I understand your question properly but I'll have a try.
If a timesheet is submitted that contains actual time against some, but not
all tasks, then the PM has to first determine whether there is an oversight.
If the timesheet is correct then some work did not get done and the PM must
reschedule the work in the plan.
If a timesheet was not submitted at all then again the PM must follow up to
find out why. If it was an oversight, then get the team member to submit the
timesheet. Sometimes th reason is as simple as the team member not pressing
the Update button to actually submit the timesheet. If the person is away
then the PM must make a judgement call and update the plan to reflect
progress. The team member must submit the timesheet on their return which may
adjust actual cost and progress.
Regardless of the reason for a missing timesheet, the team member will
receive an "Unsubmitted timesheet" message posted on their PWA Home page, and
their resource manager and the administrator will also receive a Missing
Timesheet report.