Add a way to create graphs displaying more than one array

These are important, e.g., to display a stereo signal in a single graph. Purr-Data displays these all right if I create them in another Pd flavor, and the graph canvas properties dialog also lets me delete individual arrays associated with a graph. But there doesn't seem to be a way to create a graph with multiple arrays, or add an array to an existing graph in its properties. Or am I missing something?