Appropriation Request workflow cannot be copied?

Hi Expert,

We implemented AR workflow where initially we use standard workflow WS00300022.

However, user requested several more changes like email content for approved item.

I copied the workflow and activate the event TO_BE_APPROVED for my custom workflow and deactivate it for standard workflow WS00300022.

However, if I use OITN transaction, it is as if the workflow is inactive because the t-code only display WS00300022 status but nevertheless the custom workflow is successfully triggered when I submit AR for approval.

After this activation, I notice that the behaviour of IMA11 is changed like the user exit is not triggered anymore and the system status button is not greyed out even though when I submit the AR for approval, my user is the applicant.

After further debugging, i found out that there is workflow precheck logic that only triggered if the program check that AR workflow is active.

Surprisingly, I found this code in SAP standard program while debugging :

* WF-Kopplung vorhd.

CALL FUNCTION 'SWE_EVENT_REC_TYPE_READ'

EXPORTING

OBJTYPE = 'BUS2104'

EVENT = 'TO_BE_APPROVED'

RECTYPE = 'WS00300022'

IMPORTING

TYPE_COUPLING = L_COUPLING

EXCEPTIONS

READ_FAILED = 1

OTHERS = 2.

Is it true that we cannot use custom workflow for AR and the only way to customize the workflow is to change this SAP standard workflow WS00300022?

Please help to share your experience if any expert here encounter the same issue.

FYI, my system is in ECC 6.0 EHP 3.

Thank you.

Abraham