At best you can relate a Task(s), not a whole timesheet, to an appointment(s). Then from within the Timesheet if you click on a task you can access the related appointment from the related items tab.
Not real elegant or obvious from a user standpoint but it's there.
Alternatively a user can see their own appointments, tasks and non-working time from the Calendar Tab in a nice layout.
Steve Thompson | Sr. Solutions Consultant
Daptiv