Repeat "Detail a" section when using "Format with Multiple Columns" layout

I am using Crystal Reports for .NET (VS 2008) and I would like to get the "Detail a" section to repeat at top of a second column containing additional data in "Detail b" section. Please see below for example, specifically "Detail a (2)". Any tips or help much appreciated.

Detail a (1)_____Detail a (2)

Detail b (1-1)___Detail b (2-3)

Detail b (1-2)___Detail b (2-4)

--Detail b (1-3)___Detail a (3)

Detail a (2)______--Detail b (3-1)

--Detail b (2-1)

--Detail b (2-2)

Thx, Scott