Change AWKEY & AWTYP in BKPF

Dear all,

I've looked for ways to change fields AWKEY and AWTYP in document header.

I tried FB02 but these fields are gray. It means we cannot change by FB02.

I've looked for FM BELEG_WRITE_DOCUMENT, CHANGE_DOCUMENT, FI_DOCUMENT_CHANGE.

But it seems they do not work like I expect.

Is there anyway we could do it via coding?

Thank you.