Change VA01 sreen using BADIs

Hi,

I have some requirements to add subsrceen in VA01 transaction. I have tried EXITs but didn't get much even i tried for BADIs by searching "Cl_EXITHANDLER" but found only one method:

CALL METHOD CL_EXITHANDLER=>GET_INSTANCE

EXPORTING

EXIT_NAME = 'EHS_PS_002'

NULL_INSTANCE_ACCEPTED = 'X'

IMPORTING

ACT_IMP_EXISTING = EHS_PS_002_ACTIVE

CHANGING

INSTANCE = L_BADI_INSTANCE

EXCEPTIONS

OTHERS = 1.

Please let me know how to proceed to add subscreen in VA01.

rgds

sudhanshu