REPORT Z1.
* The Z1 and Z2 reports have the same parameters...
type-pools: sscr.
DATA: SELTAB   TYPE TABLE OF RSPARAMS.

parameters: p_matnr like mara-matnr,
            p_matkl like mara-matkl. 

START-OF-SELECTION.
*1. some additional logic applied to the report Z1.
*   ...
 
*2. get Z1 parameters and select-options
  CALL FUNCTION 'RS_REFRESH_FROM_SELECTOPTIONS'
    EXPORTING
      CURR_REPORT           = sy-cprog
    TABLES
      SELECTION_TABLE       = SELTAB
    EXCEPTIONS
      NOT_FOUND             = 1
      NO_REPORT             = 2
      OTHERS                = 3.
  IF SY-SUBRC <> 0.
    MESSAGE ID SY-MSGID TYPE SY-MSGTY NUMBER SY-MSGNO
            WITH SY-MSGV1 SY-MSGV2 SY-MSGV3 SY-MSGV4.
  ENDIF.

*3. submit Z2 with Z1 parameters and select-options
  submit Z2 WITH SELECTION-TABLE seltab.
* note: no sy-subrc check is needed