Several users have requested the entries in a legend to update based on the plot visibility in Grapher. While this feature is not currently available in the Grapher interface, tech support engineer Kassi has written a script that will allow you to automatically update all legends in a visible graph to display only the plots that are currently visible. The script will loop through all the graphs in the open Grapher file and then update the legend in all the graphs that are visible. First download and upzip the UpdateLegend.zip file and then follow these instructions to use the script:
Your legend will update to contain only entries from the visible plots.