You can use OpenFI 1650 and add any fields to ALV line in FBL1N, FBL3N, FBL5N. It's simple. In this sampe you will add fields Vendor (LIFNR) and Customer (KUNNR).

Steps:
  • Include field ZZLIFNR & ZZKUNNR as add.structure in RFPOS, RFPOSX.
  • Copy func.module SAMPLE_INTERFACE_00001650 in ZFM_FBL3N and developing use ZZLIFNR & ZZKUNNR field...
FUNCTION zfm_fbl3n.
*"----------------------------------------------------------------------
*"*"Local Interface:
*"  IMPORTING
*"     VALUE(I_POSTAB) LIKE  RFPOS STRUCTURE  RFPOS
*"  EXPORTING
*"     VALUE(E_POSTAB) LIKE  RFPOS STRUCTURE  RFPOS
*"----------------------------------------------------------------------

*-------------- Initialize Output by using the following line ----------
  e_postab = i_postab.
   TABLES: lfa1, kna1, bseg.
   SELECT SINGLE lifnr kunnr
    FROM bseg INTO (e_postab-zzlifnr, e_postab-zzkunnr)
    WHERE bukrs = i_postab-bukrs
      AND gjahr = i_postab-gjahr
      AND belnr = i_postab-belnr
      AND ( kunnr  <> '' OR lifnr <> '' ).

ENDFUNCTION.

Serkan AKKAVAK
Computer Engineer
ABAP Developer & SAP MM SD Consultant
Contact : serkurumsal@yandex.com