I am looking for a method to make more compact legend entries. Suppose 3 point layers "inner", "middle", and "outer" in ArcGIS 10.7. Assume each layer has a field called measurement with a value range from 1 to 1000 symbolized by different colors. The coloration is the same for all three layers. The size of the symbol for each layer is set to a fixed amount. Layer "inner" has a small circle etc., c.f. image below.
What I would like to do, is make a merged/joined/combined symbol in the legend so that it becomes more compact, exempli gratia like so:
If you know of a better design, I am open for suggestions.
Explanation and a little bit more background
The problem arises because I want to have legend entries to explain the different colors, but as the colors appear in all three sizes, I want to also show the sizes. The automatic legend by Arc gets very very long when showing all colors for all sizes, so I'd like to first show all the colors and what they represent and then say, look, there's three sizes and the colors apply to all three sizes respectively.