DBA is not designed for manual planning.  The master schedule and all its inter-connected dates can only be generated by MRP based on item MRP settings and cannot be replicated manually.  Job release, which adjusts the schedule based on material availability, and job prioritization, which governs shop control, are dependent on the integrity of the master schedule.   The Release Jobs, Shop Control Panel, Job Schedule, and PO Schedule will not make sense unless they interact with an MRP-generated master schedule.