how leaf a blank line?

 i have a matrix report whit a conect by in the select of the rows

 i need to put a blank line before print each father except for the last

 level of the tree , how can i do ?

 (i know when change the father by a i can't put another group)

  please help

  ej.

                            92/01  92/03 92/04

          aaaaaaaa
          a1
          a2
          a3
          /*blank line*/
          bbbbbbbb
            b1
            b2
 

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