timecard template

We are implementing a new company that tracks vacation for staff employees.  Their current process is they enter the vacation time for those who have it and then generate auto time cards.  The total amount of hours is 80 and when the auto time cards are gnerated, the system takes the 80 and subtracts the vac/sick time and only adds the hours between the two.  We are on JDE E9 and can't seem to see anything in the Processing options for the timecard template that would allow us to do this.  Does anyone else do this kind of thing?  If so, how