MRP generation does not include new message of WO plan entered manually

Why does MRP (R3482) generation does not include new message of Plan WO that is entered manually by user ?

Steps :

1.  Enter forecast for item FG

2.  Enter Sales order for Item FG

3.  Run MPS generation for Item FG with planning rule C

4.  Check MPS messages - plan WO orders created for item FG

5.  However, planner sometimes want to add plan WO manually in the MPS messages (these are adhoc planning)

6.  Run MRP generation for raw materials

7.  Check MRP messages - plan PO does not include manually entered plan WO in MPS messages in step 5.

Is this std JDE planning logic or there is work around to get MRP calculated with plan manual MPS message ?