Hi,
In you can create a z class with interface IF_BSP_WD_CUSTOM_F4_CALLBACK.
In get v method of configuration item put below logic.
ls_map type if_bsp_wd_valuehelp=>gtype_param_mapping
lt_inmap type if_bsp_wd_valuehelp=>gtype_param_mapping_tab
lt_outmap type if_bsp_wd_valuehelp=>gtype_param_mapping_tab
ls_map-f4_attr = 'BP_ID'.
ls_map-context_attr = bp value.
append ls_map to lt_inmap.
append ls_map to lt_outmap.
create object rv_valuehelp_descriptor
type cl_bsp_wd_valuehelp_f4descr
exporting
iv _help_id = '(zclass)'
iv_help_id_kind = if_bsp_wd_valuehelp_f4descr=>help_id_kind_comp
iv_inputmapping= lt_inmap
iv_output_mapping = lt_outmap
iv_trigger_submit = abap_true.
Now in method if_bsp_wd_custom_f4_callback~retrieve_custom_values of your zclass put logic
check is_search_help is not initial and is_search_help-selopt is not initial.
loop at is_search_help-selopt assigning <fs_selopt>.
check <fs_selopt>-shlpfield = 'BP_ID'.
lv_bpid = <fs_selopt>-low.
endloop.
Now you have your sold to party id in lv_bpid.
now write the logic to fetch configuration items based on sold to party id and fill ct_results_tab which will your output searchhelp.
Thanks,
Tejaswini P.