ARM - BOM Conponents are not copied to SDF from RO

Hello ARM Experts,

When I save RO (RE2), having BOM, SDF (SD2) is automatically created with BOM-Header only, components are not copied. My task is to enable BOM Comps to be copied into SDF.

In debug I saw, that ARM copies only those items to SDF, which are available in Table MT_FIN_DETAIL_BUFFER. And there the items are appended at RE2 saving, if MT_FIN_STATUS_BUFFER-Paying-Status <> blank.
I assume this field Paying Status is filled from SD tables (VBAP or TVAP?), but I cannot find how it happen. MT_FIN_STATUS_BUFFER is filled from Structure IS_COMM_CTRL_DB - but from which SD fields is this structure filled, I cannot understand. We have 100% SAP-Standard in ARM, no CMOD's.
Could someone give me a hint, from which SD-Source IS_COMM_CTRL_DB-Paying_Status is filled, and where it is possible to see in Debugger?
Thanks,
Pavlo.