How to configure a variant for a material in MRP3 view using BAPI?

Which BAPI should I use in MRP3 view of MM02 transaction to create a configurable variant for a finished good material in SAP?

You should use MATERIAL_SAVE_CONFIGURATION FM like this:

1. Get configuration object for the given plant

   CALL FUNCTION 'CUXM_GET_CONFIGURATION'
     EXPORTING
       instance = ls_marc-cuobj
       werks    = ls_marc-werks
     TABLES
       t_e1cucfg = lt_e1cucfg
       t_e1cuins = lt_e1cuins
       t_e1cuval = lt_e1cuval
       t_e1cucom = lt_e1cucom
   

Alternatively, you can fill parameters manually

    lt_e1cucfg-POSEX      = '4000'.
    lt_e1cucfg-CONFIG_ID  = '000001'.
    lt_e1cucfg-ROOT_ID    = '00000001'.
    lt_e1cucfg-COMPLETE   = 'T'.
    APPEND lt_e1cucfg.

    lt_e1cuins-INST_ID       = '00000001'.
    lt_e1cuins-OBJ_TYPE      = 'MARA'.
    lt_e1cuins-CLASS_TYPE    = '300'.
    lt_e1cuins-OBJ_KEY       = 'C_GLTP'.
    lt_e1cuins-QUANTITY      = '1000'.
    lt_e1cuins-QUANTITY_UNIT = 'KG'.
    lt_e1cuins-COMPLETE      = 'T'.
    lt_e1cuins-OBJECT_GUID   = 'C_GLTP'.
    APPEND lt_e1cuins.

    lt_e1cuval-matnr         = '000000000004002322'.
    lt_e1cuval-inst_id       = '00000001'.
    lt_e1cuval-valcode       = '1'.
    lt_e1cuval-charc         = 'SHOT_PEENING_Y_N'.
    lt_e1cuval-value         = 'N'.
    APPEND lt_e1cuval.

    lt_e1cuval-charc         = 'BENDING_Y_N'.
    lt_e1cuval-value         = 'N'.
    APPEND lt_e1cuval.

    lt_e1cuval-charc         = 'LENGTH_MIN_DISCRIMINATING_MM'.
    lt_e1cuval-value         = '5000'.
    APPEND lt_e1cuval.

    lt_e1cuval-charc         = 'LENGTH_MAX_DISCRIMINATING_MM'.
    lt_e1cuval-value         = '7000'.
    APPEND lt_e1cuval.

2. Use returned values as input parameters for the MATERIAL_SAVE_CONFIGURATION

       CALL FUNCTION 'MATERIAL_SAVE_CONFIGURATION'
        EXPORTING
          material          = ls_marc-matnr
          conf_matl         = ls_mara-satnr
          plant             = ls_marc-werks
          conf_matl_plant   = ls_mara-satnr
        TABLES
          e1cucfg           = i_e1cucfg
          e1cuins           = i_e1cuins
          e1cuval           = i_e1cuval
          e1ucom            = i_e1cucom
          e1cucfg_w         = ic_e1cucfg
          e1cuins_w         = ic_e1cuins
          e1cuval_w         = i_e1cuval
          e1cucom_w         = ic_e1cucom.