How do I create a Formatted seacrh on AR doc line that referes to a previous line

I have a selectable dropdown ( user field ) in the AR document window on the  Grid Lines called Color. There are about 20 different colors.

Users select this color after the item is typed in.

However with subsequent lines I need this color to default to the first selected color.

eg:

Line 1 = Blue

Line2 =  Blue  ( auto selected based on the previous line)

Line3 =  Blue  ( auto selected based on the previous line)

Is there a way I can do this with a Formatted search rather than doing a addon for it ?