Can't edit an individual geometry element within a complex element

Hello,

I am trying to re-assign an offset dependency for a single horizontal geometry element that is a part of a much longer complex element.

The longer complex element represents an Edge of Traveled Way line that includes geometry elements such as offset partials and radii.

The single horizontal geometry element is a partial offset from an interior Edge of Pavement line.

I am replacing the interior Edge of Pavement line with a new complex horizontal geometry element, and want to use "Replace Reference" so that the single horizontal geometry element is offset from the new interior Edge of Pavement, not the old one.

However, I seem to only be able to select the entire complex Edge of Traveled Way line, not the single horizontal geometry element I want to re-assign.

I do not want to drop the Edge of Traveled Way complex element, because there are a lot of other things that depend on it, and I do not want to break the relationship.

I've tried RT-clicking to try and cycle through to the single element, but I can't seem to select it so that I can re-assign it's reference element.

Any tips here? I hope I explained it clearly enough.

Thanks!