Hi Andy - Thanks for your reply. My thinking was that with the two index formulas, I could use them as a single-point scatter. So there would be two things going on at once: 1. the line chart, and 2. the single-point - with a single horizontal and single vertical error bar (or something looking the same).
Your solution is correct; however, only needed is the current value lines, not every data point.
Is this possible? Seems this would not be especially strange in Excel graphing. The basic idea is to localize values on the axes when there are a lot of values plotted, say a hundred or so. Your thoughts?