Combining invoice printing in VF04 for same customer

Question

I have been having issues with combining the invoices and printing as one when the payer are the same. What actually is happening is: For SOrg01 customer SD transactions it checks the Invoice Split field which is currently set to "Z3 = Customer PO" for customer 1234567.  I checked the PO value for the sales orders of invoice 90109876 and 90109886 and they all have PO #A010-014, hence these two invoice should have been one.  But right the two invoices are split and printing separately instead it should have printed onto one invoice itself. I have checked the invoice splitting criteria as well as it says that when the splitting critera is set to Z3 which it is for that payer on both the invoices then only split else combine, but its not happening. I have checked all the settings on that customer but could not locate as to why this is happening.
Could anyone please suggest me as where else the problem can possibly be or located , becuase as such it should have combined together. What other tabs on teh customer data can impact this?
Thanks in advance.

Answer 1

Yes, indeed there is a logic in VFOM transaction which does the splitting based on several things. The PO numbers field I ahve checked for each and every or SO on the billing documents of both the documenst and all are the same and as for the payer , they both have the same payer for teh same sales org. and that is SO01.
CASE vbrk-vkorg.
     WHEN 'SO02'.
*     Look in Customer Sales Table for Invoicing Indicator
       SELECT SINGLE * INTO zwa_knvv FROM knvv
              WHERE vkorg EQ vbrk-vkorg AND kunnr EQ kuagv-kunnr.
       IF sy-subrc NE 0.
         zuk-vgbel = vbrp-vgbel.
       ELSE.
         CASE zwa_knvv-kvgr2.
           WHEN 'ZIS'.        " Single Location
             zuk-vgbel = vbrp-vgbel.
           WHEN 'ZIM'.        " Multiple Location
             CLEAR: zuk-vgbel, vbrk-hityp_pr.
         ENDCASE.
       ENDIF.
   ENDCASE.
*  Determine The Orders Based On Soldto Attributes
   SELECT SINGLE * INTO zwa_kna1 FROM kna1
         WHERE kunnr EQ kuagv-kunnr.
   CASE zwa_kna1-katr1.
     WHEN 'Z1'.                       " Ship-To
       zuk-kunnr_sh = kuwev-kunnr.
       CLEAR: zuk-bstkd, zuk-werks, zuk-vgbel, zuk-ihrez.
     WHEN 'Z3'.                       " Purchase Order
       zuk-bstkd = vbkd-bstkd.
       CLEAR: zuk-kunnr_sh, zuk-werks, zuk-vgbel, zuk-ihrez.
     WHEN 'Z4'.                       " AFE
       zuk-ihrez = vbkd-ihrez.
       CLEAR: zuk-kunnr_sh, zuk-werks, zuk-vgbel, zuk-bstkd.
     WHEN 'Z5'.                       " Plant
       zuk-werks = vbrp-werks.
       CLEAR: zuk-kunnr_sh, zuk-ihrez, zuk-vgbel, zuk-bstkd.
     WHEN 'Z6'.                       " Sales Order
       zuk-vgbel = vbrp-aubel.
       CLEAR: zuk-kunnr_sh, zuk-ihrez, zuk-werks, zuk-bstkd.