plotting graphs in hfss

i have 2 graphs for the calculation of s parameter for 2 different design..under same project

how can i show these 2 graphs on one single graph in hfss..

on the traces window (where you select what you want to plot)
go to sweep,
and change the radio button to "Sweep Design and project variable values")

then select what you to plot. make sure at least of your values is the primary sweep or what appears on the x-axis. whatever variable left is done as an extra plot