Be able to edit timesheet entries from an approved PTO request

Currently one of the biggest problems I have is not being able to edit timesheet entries that have been automatically entered for an approved PTO request. If an employee takes PTO during a week we usually limit their total worked and PTO hours to 40 per week as to help them conserve their PTO. But for example if an employee puts in a request for 8 hours but the rest of the week they work 33 hours that will total 41 hours. I am not able to edit the entry though. I have to back and deny the request and then enter the correct hours for that day. I am aware that this problem may be unique to our company. But if not, it would be great if I would be able to edit timesheet entries from an approved PTO request.