PowerBuilder DW PFC

I have a 3 PFC datawindows on a page.  
   DW#1 is a master list.  
   DW#2 is the detail of the row selected from DW#1.  
   DW#3 is a list (comes from another table) based on the row selected from DW#1.

When the user clicks the save button the pfc takes care of updating any changes in DW#2.  

The save button will also update any rows in DW#3 (two of the columns are updatable in this DW).  

There is also a delete button.  When the user clicks it, it deletes the row from DW#1 & DW#2.  I presumed it would also delete the rows from DW#3 but it does not seem to work.
I tried using the RowsMove method to put them into the delete buffer first.   This removes them visually from the DW#3 but it does not remove them from the underlying db table.

Am I missing something?

Here is a code snippet.

cb_delete.clicked() event
-----------------------------------
int li_rc, li_rowcount
li_rowcount = dw_3.rowcount()
li_rc=dw_3.RowsMove(1, li_rowcount, Primary!,  dw_3, 1, Delete!)

call super::clicked