Rule_Context_Prepare BADI for Supplier Scenario

Hi MDG Experts,

I have a scenario where, in case of change Supplier change request (ZSUP02, We have configured rule based workflow WS60800086), when a User change payment term or partner function then workflow should go to approver A, if payment terms and partner function is not changed then it should go to approver B.

For above scenario i am trying to implement Rule_Context_Prepare BADI. But i am getting below problem:-

1) I am not able to fetch data from UI. Can you please let me know which method should i use to do it or is there any other way. When i am trying to use below standard method, i am getting activated data from backend table, but i need data from UI in order to get the changes in payment term or partner function .

CALL METHOD lr_model->read_char_value

    EXPORTING

      i_fieldname       = 'BP_PORG' " i tried to use BP_PORG entity as i was thinking i might get UI data, but no win.

      it_sel            = lt_sel

      i_readmode        = if_usmd_model_ext=>gc_readmode_default

      if_use_edtn_slice = abap_false

    IMPORTING

      et_data           = <lt_data>.

2) How to get BRF application ID for change request ZSUP02.

3) Structure name for supplier which will hold all the fields specially payment term and partner function fields. (for example for material we have /mdgmm/_s_mm_pp_material)

I am following below document :-

http://www.sdn.sap.com/irj/scn/go/portal/prtroot/docs/library/uuid/60f0cc68-5884-2e10-b8a9-a71ba25ad1ad?QuickLink=index&…

Thanks

Regards

Nitish Sharma