To answer your last question first, yes it is possible to generate an Absence Quota Allowance from Attendance Types.
Use the Time Evaluation log to study your current Time Evaluation Schema and Rules. Identify where the Attendances are currently processed, what Time Types are generated when the Planned Work Time is processed, when the Attendances are processed, and wether "Overtime" Time Types are currently generated (for the difference between Planned hours and Worked hours).
In your decision process, what information is required from the "previous day"? Is that information currently being generated "today" and transfered to table ZES so that it could easily be read the following day?
You may need to create a new Absence Quota whose Allowance would be generated though a pcr and for whom an Absence would enable the employee to use it.
You may require to create new Time Types (for the Quota Allowance, the CompOff Absence, the Information Time Types, etc.).
Also map out your requirements more clearly. "09.30" is a number of hours while "09:30" is a time of day.
What are the thresholds that define what will be "carried forward to next day" and what will generate one or two "comp days off"? Is it the same requirement for employees working on 7 hrs shifts as for those working on 9½ hrs shifts?
