Hi All,
I found the way to force update work order header change using following code:
CALL FUNCTION 'CO_IH_SET_HEADER'
EXPORTING CAUFVD_IMP = CAUFVD_IMP.
PERFORM HEADER_UPDATE(SAPLCOIH).
It's explained in following thread https://scn.sap.com/thread/3697460
Regards
Hadi