I am running classic MRP for single material from MD02. I have created requirements manually from MD61. After generating schedule lines and releasing them to Vendor(checked IDOC sent correctly), I have increased requirements for next month and run MRP again. In scheduling agreement there is firm zone and trade off zone set and binding on MRP is 1 to keep schedule lines on firm zone unchanged. MRP is not changing quantity or date of existing schedule lines on firm zone instead it has created one more schedule line to firm zone. What I expect MRP should reschedule requirement that is not covered with firmed schedule lines to non firmed zone. How can I achieve that ?