Quote - "Is there a special setting in GC2 for zero edging? If so, could you point it out to me? I always "zero" edged by using the dark blue lowest altitude setting around the front edge or side edges."

I zero-edge in GC2 like this: Filter tab -> Add -> General forming -> Zero-edge.

After this filter is applied, you can change and experiment with "general strength" and "Border", both in the Settings tab of this particular filter. With "border" you can define how gradual the effect is applied.
You can also go to tab "level control" of that filter and play with all the levels and again obtain completely different results.

If you make selections on your terrain, you can also apply the settings depending on your selection. This is a general possibility for all filters, including this one, although I never used it for this one.