From: Qi An on
I have a figure with 3 axes, each of which has a legend. I DON'T know the handles of legends.

Now I have plotted a new line on each of axes and I want to add one additional line to existing legends. How can I do that?

Basically, my two questions are,
1) how to find the handle of legend associated with one particular axis?
2) how to add one additonal line to existing legend?

Thanks!