many thanks @Shimwell; indeed the isotope plotter is able to give several XS on the same plot…it will be nice if the same option will be available on the material plotter.
What I can do, is to plot each element alone and download the data, it will be easier to plot them on the same figure using matplotlib. It will be just tricky to set the x-axis correctly when plotting different data sets with different xdata on the same intervall, but it will be possible.