Drilldown to Base Member

One of my users has requested an eExcel report that will drilldown to the base members rather than the next level when they double click on a row. In the example below, if Parent is doubleclicked, the user would like to see A,B,C,D,E instead of Child1,Child2,Child3. Is there any way to do this? I realize that I can set up the report to show the parent and the base members, but the user is requesting a collapsed report at the parent level that allows them to drilldown on the parent(s) they wish. Any ideas???

Parent
    Child1
      A
      B
    Child2
      C
      D
    Child3
      E

Thanks!

~Alison