Slab edges with a depression to accommodate a Window wall seems to be somewhat pesky at this point. That is because the Slab-edge family within Revit is additive. So, if your slab edge is smaller than the depth of the slab, then you have to pull the slab boundary towards the interior of the building and then add the slab-edge family as an extension to the slab. In short, this workflow is less than ideal both in terms of performing the actual work and in terms of managing the model in the long run.
