How to hide total row if only one child

Using SSRS 2008 R2 to create a simple hierarchical report using BIDS. The child rows have the detail data. There are then 2 total levels, dad and grandpa. Generally each level of parent has multiple children and the parent rows are just sums of the detail data. In some cases a parent only has 1 child, so both child and parent have identical sums. When that happens, I need to hide the parent row. My problem is not how to hide, but rather how to use an expression to identify a parent row that only has one child above it.

Thanks.