RowValidating in master/detail scenario

Question

simple or not tht is .... ?
I have two DataViewGrids , for master and detail record.
I have RowValidating on second grid to suspend blank cell.
Now:
    if changes parent record RowValidating on current detail record do:
    1) validation current detail record (index 3)
    2)  datagridview get new set detail records (in my case one row)
      
    3) RowValidating validation again row index 3 !!!
    4) Than validation new record index 0
  In grid now I have one  OK row - index 0 and three blank rows
  (grid is not reefresh )
 Without RowValidating bind work fine   
How I can suspend validation old (blank) row ?